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_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 70 static int cpu_subsys_offline(struct device *dev) 71 { 72 return cpu_down(dev->id); 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 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 } 162 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 163 164 static 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 } 173 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL); 174 175 static struct attribute *crash_note_cpu_attrs[] = { 176 &dev_attr_crash_notes.attr, 177 &dev_attr_crash_notes_size.attr, 178 NULL 179 }; 180 181 static struct attribute_group crash_note_cpu_attr_group = { 182 .attrs = crash_note_cpu_attrs, 183 }; 184 #endif 185 186 static const struct attribute_group *common_cpu_attr_groups[] = { 187 #ifdef CONFIG_KEXEC 188 &crash_note_cpu_attr_group, 189 #endif 190 NULL 191 }; 192 193 static 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 */ 203 204 struct cpu_attr { 205 struct device_attribute attr; 206 const struct cpumask *const map; 207 }; 208 209 static 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 */ 222 static 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 */ 231 static 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 } 237 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 238 239 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 240 unsigned int total_cpus; 241 242 static 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 } 270 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 271 272 static 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 } 289 static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL); 290 291 #ifdef CONFIG_NO_HZ_FULL 292 static 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 } 301 static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL); 302 #endif 303 304 static 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 324 static 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 } 345 346 static 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 */ 366 int 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 return error; 387 388 per_cpu(cpu_sys_devices, num) = &cpu->dev; 389 register_cpu_under_node(num, cpu_to_node(num)); 390 dev_pm_qos_expose_latency_limit(&cpu->dev, 391 PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); 392 393 return 0; 394 } 395 396 struct device *get_cpu_device(unsigned cpu) 397 { 398 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 399 return per_cpu(cpu_sys_devices, cpu); 400 else 401 return NULL; 402 } 403 EXPORT_SYMBOL_GPL(get_cpu_device); 404 405 static void device_create_release(struct device *dev) 406 { 407 kfree(dev); 408 } 409 410 static struct device * 411 __cpu_device_create(struct device *parent, void *drvdata, 412 const struct attribute_group **groups, 413 const char *fmt, va_list args) 414 { 415 struct device *dev = NULL; 416 int retval = -ENODEV; 417 418 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 419 if (!dev) { 420 retval = -ENOMEM; 421 goto error; 422 } 423 424 device_initialize(dev); 425 dev->parent = parent; 426 dev->groups = groups; 427 dev->release = device_create_release; 428 dev_set_drvdata(dev, drvdata); 429 430 retval = kobject_set_name_vargs(&dev->kobj, fmt, args); 431 if (retval) 432 goto error; 433 434 retval = device_add(dev); 435 if (retval) 436 goto error; 437 438 return dev; 439 440 error: 441 put_device(dev); 442 return ERR_PTR(retval); 443 } 444 445 struct device *cpu_device_create(struct device *parent, void *drvdata, 446 const struct attribute_group **groups, 447 const char *fmt, ...) 448 { 449 va_list vargs; 450 struct device *dev; 451 452 va_start(vargs, fmt); 453 dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs); 454 va_end(vargs); 455 return dev; 456 } 457 EXPORT_SYMBOL_GPL(cpu_device_create); 458 459 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 460 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL); 461 #endif 462 463 static struct attribute *cpu_root_attrs[] = { 464 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 465 &dev_attr_probe.attr, 466 &dev_attr_release.attr, 467 #endif 468 &cpu_attrs[0].attr.attr, 469 &cpu_attrs[1].attr.attr, 470 &cpu_attrs[2].attr.attr, 471 &dev_attr_kernel_max.attr, 472 &dev_attr_offline.attr, 473 &dev_attr_isolated.attr, 474 #ifdef CONFIG_NO_HZ_FULL 475 &dev_attr_nohz_full.attr, 476 #endif 477 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 478 &dev_attr_modalias.attr, 479 #endif 480 NULL 481 }; 482 483 static struct attribute_group cpu_root_attr_group = { 484 .attrs = cpu_root_attrs, 485 }; 486 487 static const struct attribute_group *cpu_root_attr_groups[] = { 488 &cpu_root_attr_group, 489 NULL, 490 }; 491 492 bool cpu_is_hotpluggable(unsigned cpu) 493 { 494 struct device *dev = get_cpu_device(cpu); 495 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 496 } 497 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 498 499 #ifdef CONFIG_GENERIC_CPU_DEVICES 500 static DEFINE_PER_CPU(struct cpu, cpu_devices); 501 #endif 502 503 static void __init cpu_dev_register_generic(void) 504 { 505 #ifdef CONFIG_GENERIC_CPU_DEVICES 506 int i; 507 508 for_each_possible_cpu(i) { 509 if (register_cpu(&per_cpu(cpu_devices, i), i)) 510 panic("Failed to register CPU device"); 511 } 512 #endif 513 } 514 515 #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES 516 517 ssize_t __weak cpu_show_meltdown(struct device *dev, 518 struct device_attribute *attr, char *buf) 519 { 520 return sprintf(buf, "Not affected\n"); 521 } 522 523 ssize_t __weak cpu_show_spectre_v1(struct device *dev, 524 struct device_attribute *attr, char *buf) 525 { 526 return sprintf(buf, "Not affected\n"); 527 } 528 529 ssize_t __weak cpu_show_spectre_v2(struct device *dev, 530 struct device_attribute *attr, char *buf) 531 { 532 return sprintf(buf, "Not affected\n"); 533 } 534 535 static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL); 536 static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL); 537 static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL); 538 539 static struct attribute *cpu_root_vulnerabilities_attrs[] = { 540 &dev_attr_meltdown.attr, 541 &dev_attr_spectre_v1.attr, 542 &dev_attr_spectre_v2.attr, 543 NULL 544 }; 545 546 static const struct attribute_group cpu_root_vulnerabilities_group = { 547 .name = "vulnerabilities", 548 .attrs = cpu_root_vulnerabilities_attrs, 549 }; 550 551 static void __init cpu_register_vulnerabilities(void) 552 { 553 if (sysfs_create_group(&cpu_subsys.dev_root->kobj, 554 &cpu_root_vulnerabilities_group)) 555 pr_err("Unable to register CPU vulnerabilities\n"); 556 } 557 558 #else 559 static inline void cpu_register_vulnerabilities(void) { } 560 #endif 561 562 void __init cpu_dev_init(void) 563 { 564 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 565 panic("Failed to register CPU subsystem"); 566 567 cpu_dev_register_generic(); 568 cpu_register_vulnerabilities(); 569 } 570