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 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 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 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 const 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 static 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 */ 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 static ssize_t print_cpus_kernel_max(struct device *dev, 229 struct device_attribute *attr, char *buf) 230 { 231 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 static ssize_t print_cpus_offline(struct device *dev, 239 struct device_attribute *attr, char *buf) 240 { 241 int len = 0; 242 cpumask_var_t offline; 243 244 /* display offline cpus < nr_cpu_ids */ 245 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 246 return -ENOMEM; 247 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); 248 len += sysfs_emit_at(buf, len, "%*pbl", cpumask_pr_args(offline)); 249 free_cpumask_var(offline); 250 251 /* display offline cpus >= nr_cpu_ids */ 252 if (total_cpus && nr_cpu_ids < total_cpus) { 253 len += sysfs_emit_at(buf, len, ","); 254 255 if (nr_cpu_ids == total_cpus-1) 256 len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids); 257 else 258 len += sysfs_emit_at(buf, len, "%u-%d", 259 nr_cpu_ids, total_cpus - 1); 260 } 261 262 len += sysfs_emit_at(buf, len, "\n"); 263 264 return len; 265 } 266 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 267 268 static ssize_t print_cpus_isolated(struct device *dev, 269 struct device_attribute *attr, char *buf) 270 { 271 int len; 272 cpumask_var_t isolated; 273 274 if (!alloc_cpumask_var(&isolated, GFP_KERNEL)) 275 return -ENOMEM; 276 277 cpumask_andnot(isolated, cpu_possible_mask, 278 housekeeping_cpumask(HK_FLAG_DOMAIN)); 279 len = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(isolated)); 280 281 free_cpumask_var(isolated); 282 283 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 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 } 314 315 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 316 static ssize_t print_cpu_modalias(struct device *dev, 317 struct device_attribute *attr, 318 char *buf) 319 { 320 int len = 0; 321 u32 i; 322 323 len += sysfs_emit_at(buf, len, 324 "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:", 325 CPU_FEATURE_TYPEVAL); 326 327 for (i = 0; i < MAX_CPU_FEATURES; i++) 328 if (cpu_have_feature(i)) { 329 if (len + sizeof(",XXXX\n") >= PAGE_SIZE) { 330 WARN(1, "CPU features overflow page\n"); 331 break; 332 } 333 len += sysfs_emit_at(buf, len, ",%04X", i); 334 } 335 len += sysfs_emit_at(buf, len, "\n"); 336 return len; 337 } 338 339 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env) 340 { 341 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); 342 if (buf) { 343 print_cpu_modalias(NULL, NULL, buf); 344 add_uevent_var(env, "MODALIAS=%s", buf); 345 kfree(buf); 346 } 347 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 int register_cpu(struct cpu *cpu, int num) 360 { 361 int error; 362 363 cpu->node_id = cpu_to_node(num); 364 memset(&cpu->dev, 0x00, sizeof(struct device)); 365 cpu->dev.id = num; 366 cpu->dev.bus = &cpu_subsys; 367 cpu->dev.release = cpu_device_release; 368 cpu->dev.offline_disabled = !cpu->hotpluggable; 369 cpu->dev.offline = !cpu_online(num); 370 cpu->dev.of_node = of_get_cpu_node(num, NULL); 371 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 372 cpu->dev.bus->uevent = cpu_uevent; 373 #endif 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 } 390 391 struct device *get_cpu_device(unsigned 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 } 398 EXPORT_SYMBOL_GPL(get_cpu_device); 399 400 static void device_create_release(struct device *dev) 401 { 402 kfree(dev); 403 } 404 405 __printf(4, 0) 406 static 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; 434 435 error: 436 put_device(dev); 437 return ERR_PTR(retval); 438 } 439 440 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 va_start(vargs, fmt); 448 dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs); 449 va_end(vargs); 450 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 bool cpu_is_hotpluggable(unsigned cpu) 488 { 489 struct device *dev = get_cpu_device(cpu); 490 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 static void __init cpu_dev_register_generic(void) 499 { 500 #ifdef CONFIG_GENERIC_CPU_DEVICES 501 int i; 502 503 for_each_possible_cpu(i) { 504 if (register_cpu(&per_cpu(cpu_devices, i), i)) 505 panic("Failed to register CPU device"); 506 } 507 #endif 508 } 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 static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL); 568 static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL); 569 static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL); 570 static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL); 571 static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL); 572 static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL); 573 static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL); 574 static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL); 575 static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL); 576 577 static struct attribute *cpu_root_vulnerabilities_attrs[] = { 578 &dev_attr_meltdown.attr, 579 &dev_attr_spectre_v1.attr, 580 &dev_attr_spectre_v2.attr, 581 &dev_attr_spec_store_bypass.attr, 582 &dev_attr_l1tf.attr, 583 &dev_attr_mds.attr, 584 &dev_attr_tsx_async_abort.attr, 585 &dev_attr_itlb_multihit.attr, 586 &dev_attr_srbds.attr, 587 NULL 588 }; 589 590 static const struct attribute_group cpu_root_vulnerabilities_group = { 591 .name = "vulnerabilities", 592 .attrs = cpu_root_vulnerabilities_attrs, 593 }; 594 595 static void __init cpu_register_vulnerabilities(void) 596 { 597 if (sysfs_create_group(&cpu_subsys.dev_root->kobj, 598 &cpu_root_vulnerabilities_group)) 599 pr_err("Unable to register CPU vulnerabilities\n"); 600 } 601 602 #else 603 static inline void cpu_register_vulnerabilities(void) { } 604 #endif 605 606 void __init cpu_dev_init(void) 607 { 608 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 609 panic("Failed to register CPU subsystem"); 610 611 cpu_dev_register_generic(); 612 cpu_register_vulnerabilities(); 613 } 614