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 : return 0;
35 : }
36 :
37 : #ifdef CONFIG_HOTPLUG_CPU
38 : static 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 :
47 : static 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 :
70 : static int cpu_subsys_offline(struct device *dev)
71 : {
72 : return cpu_device_down(dev);
73 : }
74 :
75 : void 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
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 : #ifdef CONFIG_KEXEC
129 : #include <linux/kexec.h>
130 :
131 : static 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 : }
151 : static DEVICE_ATTR_ADMIN_RO(crash_notes);
152 :
153 : static 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 : }
159 : static DEVICE_ATTR_ADMIN_RO(crash_notes_size);
160 :
161 : static struct attribute *crash_note_cpu_attrs[] = {
162 : &dev_attr_crash_notes.attr,
163 : &dev_attr_crash_notes_size.attr,
164 : NULL
165 : };
166 :
167 : static const struct attribute_group crash_note_cpu_attr_group = {
168 : .attrs = crash_note_cpu_attrs,
169 : };
170 : #endif
171 :
172 : static const struct attribute_group *common_cpu_attr_groups[] = {
173 : #ifdef CONFIG_KEXEC
174 : &crash_note_cpu_attr_group,
175 : #endif
176 : NULL
177 : };
178 :
179 : static 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 :
190 : struct cpu_attr {
191 : struct device_attribute attr;
192 : const struct cpumask *const map;
193 : };
194 :
195 0 : static ssize_t show_cpus_attr(struct device *dev,
196 : struct device_attribute *attr,
197 : char *buf)
198 : {
199 0 : struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
200 :
201 0 : 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 */
208 : static 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 : */
217 0 : static ssize_t print_cpus_kernel_max(struct device *dev,
218 : struct device_attribute *attr, char *buf)
219 : {
220 0 : return sysfs_emit(buf, "%d\n", NR_CPUS - 1);
221 : }
222 : static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
223 :
224 : /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
225 : unsigned int total_cpus;
226 :
227 0 : static ssize_t print_cpus_offline(struct device *dev,
228 : struct device_attribute *attr, char *buf)
229 : {
230 0 : int len = 0;
231 : cpumask_var_t offline;
232 :
233 : /* display offline cpus < nr_cpu_ids */
234 0 : if (!alloc_cpumask_var(&offline, GFP_KERNEL))
235 : return -ENOMEM;
236 0 : cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
237 0 : len += sysfs_emit_at(buf, len, "%*pbl", cpumask_pr_args(offline));
238 0 : free_cpumask_var(offline);
239 :
240 : /* display offline cpus >= nr_cpu_ids */
241 0 : if (total_cpus && nr_cpu_ids < total_cpus) {
242 0 : len += sysfs_emit_at(buf, len, ",");
243 :
244 0 : if (nr_cpu_ids == total_cpus-1)
245 0 : len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids);
246 : else
247 0 : len += sysfs_emit_at(buf, len, "%u-%d",
248 : nr_cpu_ids, total_cpus - 1);
249 : }
250 :
251 0 : len += sysfs_emit_at(buf, len, "\n");
252 :
253 0 : return len;
254 : }
255 : static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
256 :
257 0 : static 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 0 : if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
264 : return -ENOMEM;
265 :
266 0 : cpumask_andnot(isolated, cpu_possible_mask,
267 : housekeeping_cpumask(HK_TYPE_DOMAIN));
268 0 : len = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(isolated));
269 :
270 0 : free_cpumask_var(isolated);
271 :
272 0 : return len;
273 : }
274 : static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
275 :
276 : #ifdef CONFIG_NO_HZ_FULL
277 : static 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 : }
282 : static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
283 : #endif
284 :
285 0 : static 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 0 : }
303 :
304 : #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
305 : static 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 :
328 : static 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 :
340 : struct 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 : };
352 : EXPORT_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 : */
362 1 : int register_cpu(struct cpu *cpu, int num)
363 : {
364 : int error;
365 :
366 1 : cpu->node_id = cpu_to_node(num);
367 1 : memset(&cpu->dev, 0x00, sizeof(struct device));
368 1 : cpu->dev.id = num;
369 1 : cpu->dev.bus = &cpu_subsys;
370 1 : cpu->dev.release = cpu_device_release;
371 1 : cpu->dev.offline_disabled = !cpu->hotpluggable;
372 1 : cpu->dev.offline = !cpu_online(num);
373 1 : cpu->dev.of_node = of_get_cpu_node(num, NULL);
374 1 : cpu->dev.groups = common_cpu_attr_groups;
375 1 : if (cpu->hotpluggable)
376 0 : cpu->dev.groups = hotplugable_cpu_attr_groups;
377 1 : error = device_register(&cpu->dev);
378 1 : if (error) {
379 0 : put_device(&cpu->dev);
380 0 : return error;
381 : }
382 :
383 1 : per_cpu(cpu_sys_devices, num) = &cpu->dev;
384 1 : register_cpu_under_node(num, cpu_to_node(num));
385 1 : dev_pm_qos_expose_latency_limit(&cpu->dev,
386 : PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
387 :
388 1 : return 0;
389 : }
390 :
391 1 : struct device *get_cpu_device(unsigned int cpu)
392 : {
393 1 : if (cpu < nr_cpu_ids && cpu_possible(cpu))
394 1 : return per_cpu(cpu_sys_devices, cpu);
395 : else
396 : 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 0 : __cpu_device_create(struct device *parent, void *drvdata,
408 : const struct attribute_group **groups,
409 : const char *fmt, va_list args)
410 : {
411 0 : struct device *dev = NULL;
412 0 : int retval = -ENOMEM;
413 :
414 0 : dev = kzalloc(sizeof(*dev), GFP_KERNEL);
415 0 : if (!dev)
416 : goto error;
417 :
418 0 : device_initialize(dev);
419 0 : dev->parent = parent;
420 0 : dev->groups = groups;
421 0 : dev->release = device_create_release;
422 0 : device_set_pm_not_required(dev);
423 0 : dev_set_drvdata(dev, drvdata);
424 :
425 0 : retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
426 0 : if (retval)
427 : goto error;
428 :
429 0 : retval = device_add(dev);
430 0 : if (retval)
431 : goto error;
432 :
433 : return dev;
434 :
435 : error:
436 0 : put_device(dev);
437 0 : return ERR_PTR(retval);
438 : }
439 :
440 0 : struct 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 0 : va_start(vargs, fmt);
448 0 : dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
449 0 : va_end(vargs);
450 0 : return dev;
451 : }
452 : EXPORT_SYMBOL_GPL(cpu_device_create);
453 :
454 : #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
455 : static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
456 : #endif
457 :
458 : static 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 :
478 : static const struct attribute_group cpu_root_attr_group = {
479 : .attrs = cpu_root_attrs,
480 : };
481 :
482 : static const struct attribute_group *cpu_root_attr_groups[] = {
483 : &cpu_root_attr_group,
484 : NULL,
485 : };
486 :
487 0 : bool cpu_is_hotpluggable(unsigned int cpu)
488 : {
489 0 : struct device *dev = get_cpu_device(cpu);
490 0 : return dev && container_of(dev, struct cpu, dev)->hotpluggable;
491 : }
492 : EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
493 :
494 : #ifdef CONFIG_GENERIC_CPU_DEVICES
495 : static DEFINE_PER_CPU(struct cpu, cpu_devices);
496 : #endif
497 :
498 1 : static void __init cpu_dev_register_generic(void)
499 : {
500 : #ifdef CONFIG_GENERIC_CPU_DEVICES
501 : int i;
502 :
503 2 : for_each_possible_cpu(i) {
504 1 : if (register_cpu(&per_cpu(cpu_devices, i), i))
505 0 : panic("Failed to register CPU device");
506 : }
507 : #endif
508 1 : }
509 :
510 : #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
511 :
512 : ssize_t __weak cpu_show_meltdown(struct device *dev,
513 : struct device_attribute *attr, char *buf)
514 : {
515 : return sysfs_emit(buf, "Not affected\n");
516 : }
517 :
518 : ssize_t __weak cpu_show_spectre_v1(struct device *dev,
519 : struct device_attribute *attr, char *buf)
520 : {
521 : return sysfs_emit(buf, "Not affected\n");
522 : }
523 :
524 : ssize_t __weak cpu_show_spectre_v2(struct device *dev,
525 : struct device_attribute *attr, char *buf)
526 : {
527 : return sysfs_emit(buf, "Not affected\n");
528 : }
529 :
530 : ssize_t __weak cpu_show_spec_store_bypass(struct device *dev,
531 : struct device_attribute *attr, char *buf)
532 : {
533 : return sysfs_emit(buf, "Not affected\n");
534 : }
535 :
536 : ssize_t __weak cpu_show_l1tf(struct device *dev,
537 : struct device_attribute *attr, char *buf)
538 : {
539 : return sysfs_emit(buf, "Not affected\n");
540 : }
541 :
542 : ssize_t __weak cpu_show_mds(struct device *dev,
543 : struct device_attribute *attr, char *buf)
544 : {
545 : return sysfs_emit(buf, "Not affected\n");
546 : }
547 :
548 : ssize_t __weak cpu_show_tsx_async_abort(struct device *dev,
549 : struct device_attribute *attr,
550 : char *buf)
551 : {
552 : return sysfs_emit(buf, "Not affected\n");
553 : }
554 :
555 : ssize_t __weak cpu_show_itlb_multihit(struct device *dev,
556 : struct device_attribute *attr, char *buf)
557 : {
558 : return sysfs_emit(buf, "Not affected\n");
559 : }
560 :
561 : ssize_t __weak cpu_show_srbds(struct device *dev,
562 : struct device_attribute *attr, char *buf)
563 : {
564 : return sysfs_emit(buf, "Not affected\n");
565 : }
566 :
567 : ssize_t __weak cpu_show_mmio_stale_data(struct device *dev,
568 : struct device_attribute *attr, char *buf)
569 : {
570 : return sysfs_emit(buf, "Not affected\n");
571 : }
572 :
573 : ssize_t __weak cpu_show_retbleed(struct device *dev,
574 : struct device_attribute *attr, char *buf)
575 : {
576 : return sysfs_emit(buf, "Not affected\n");
577 : }
578 :
579 : static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
580 : static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
581 : static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
582 : static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
583 : static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);
584 : static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
585 : static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
586 : static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
587 : static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
588 : static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
589 : static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL);
590 :
591 : static struct attribute *cpu_root_vulnerabilities_attrs[] = {
592 : &dev_attr_meltdown.attr,
593 : &dev_attr_spectre_v1.attr,
594 : &dev_attr_spectre_v2.attr,
595 : &dev_attr_spec_store_bypass.attr,
596 : &dev_attr_l1tf.attr,
597 : &dev_attr_mds.attr,
598 : &dev_attr_tsx_async_abort.attr,
599 : &dev_attr_itlb_multihit.attr,
600 : &dev_attr_srbds.attr,
601 : &dev_attr_mmio_stale_data.attr,
602 : &dev_attr_retbleed.attr,
603 : NULL
604 : };
605 :
606 : static const struct attribute_group cpu_root_vulnerabilities_group = {
607 : .name = "vulnerabilities",
608 : .attrs = cpu_root_vulnerabilities_attrs,
609 : };
610 :
611 : static void __init cpu_register_vulnerabilities(void)
612 : {
613 : struct device *dev = bus_get_dev_root(&cpu_subsys);
614 :
615 : if (dev) {
616 : if (sysfs_create_group(&dev->kobj, &cpu_root_vulnerabilities_group))
617 : pr_err("Unable to register CPU vulnerabilities\n");
618 : put_device(dev);
619 : }
620 : }
621 :
622 : #else
623 : static inline void cpu_register_vulnerabilities(void) { }
624 : #endif
625 :
626 1 : void __init cpu_dev_init(void)
627 : {
628 1 : if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
629 0 : panic("Failed to register CPU subsystem");
630 :
631 1 : cpu_dev_register_generic();
632 : cpu_register_vulnerabilities();
633 1 : }
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