1 /* 2 * CPU subsystem support 3 */ 4 5 #include <linux/kernel.h> 6 #include <linux/module.h> 7 #include <linux/init.h> 8 #include <linux/sched.h> 9 #include <linux/cpu.h> 10 #include <linux/topology.h> 11 #include <linux/device.h> 12 #include <linux/node.h> 13 #include <linux/gfp.h> 14 #include <linux/slab.h> 15 #include <linux/percpu.h> 16 #include <linux/acpi.h> 17 #include <linux/of.h> 18 #include <linux/cpufeature.h> 19 20 #include "base.h" 21 22 static DEFINE_PER_CPU(struct device *, cpu_sys_devices); 23 24 static int cpu_subsys_match(struct device *dev, struct device_driver *drv) 25 { 26 /* ACPI style match is the only one that may succeed. */ 27 if (acpi_driver_match_device(dev, drv)) 28 return 1; 29 30 return 0; 31 } 32 33 #ifdef CONFIG_HOTPLUG_CPU 34 static void change_cpu_under_node(struct cpu *cpu, 35 unsigned int from_nid, unsigned int to_nid) 36 { 37 int cpuid = cpu->dev.id; 38 unregister_cpu_under_node(cpuid, from_nid); 39 register_cpu_under_node(cpuid, to_nid); 40 cpu->node_id = to_nid; 41 } 42 43 static int __ref cpu_subsys_online(struct device *dev) 44 { 45 struct cpu *cpu = container_of(dev, struct cpu, dev); 46 int cpuid = dev->id; 47 int from_nid, to_nid; 48 int ret; 49 50 from_nid = cpu_to_node(cpuid); 51 if (from_nid == NUMA_NO_NODE) 52 return -ENODEV; 53 54 ret = cpu_up(cpuid); 55 /* 56 * When hot adding memory to memoryless node and enabling a cpu 57 * on the node, node number of the cpu may internally change. 58 */ 59 to_nid = cpu_to_node(cpuid); 60 if (from_nid != to_nid) 61 change_cpu_under_node(cpu, from_nid, to_nid); 62 63 return ret; 64 } 65 66 static int cpu_subsys_offline(struct device *dev) 67 { 68 return cpu_down(dev->id); 69 } 70 71 void unregister_cpu(struct cpu *cpu) 72 { 73 int logical_cpu = cpu->dev.id; 74 75 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 76 77 device_unregister(&cpu->dev); 78 per_cpu(cpu_sys_devices, logical_cpu) = NULL; 79 return; 80 } 81 82 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 83 static ssize_t cpu_probe_store(struct device *dev, 84 struct device_attribute *attr, 85 const char *buf, 86 size_t count) 87 { 88 ssize_t cnt; 89 int ret; 90 91 ret = lock_device_hotplug_sysfs(); 92 if (ret) 93 return ret; 94 95 cnt = arch_cpu_probe(buf, count); 96 97 unlock_device_hotplug(); 98 return cnt; 99 } 100 101 static ssize_t cpu_release_store(struct device *dev, 102 struct device_attribute *attr, 103 const char *buf, 104 size_t count) 105 { 106 ssize_t cnt; 107 int ret; 108 109 ret = lock_device_hotplug_sysfs(); 110 if (ret) 111 return ret; 112 113 cnt = arch_cpu_release(buf, count); 114 115 unlock_device_hotplug(); 116 return cnt; 117 } 118 119 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); 120 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); 121 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ 122 #endif /* CONFIG_HOTPLUG_CPU */ 123 124 struct bus_type cpu_subsys = { 125 .name = "cpu", 126 .dev_name = "cpu", 127 .match = cpu_subsys_match, 128 #ifdef CONFIG_HOTPLUG_CPU 129 .online = cpu_subsys_online, 130 .offline = cpu_subsys_offline, 131 #endif 132 }; 133 EXPORT_SYMBOL_GPL(cpu_subsys); 134 135 #ifdef CONFIG_KEXEC 136 #include <linux/kexec.h> 137 138 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr, 139 char *buf) 140 { 141 struct cpu *cpu = container_of(dev, struct cpu, dev); 142 ssize_t rc; 143 unsigned long long addr; 144 int cpunum; 145 146 cpunum = cpu->dev.id; 147 148 /* 149 * Might be reading other cpu's data based on which cpu read thread 150 * has been scheduled. But cpu data (memory) is allocated once during 151 * boot up and this data does not change there after. Hence this 152 * operation should be safe. No locking required. 153 */ 154 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); 155 rc = sprintf(buf, "%Lx\n", addr); 156 return rc; 157 } 158 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 159 160 static ssize_t show_crash_notes_size(struct device *dev, 161 struct device_attribute *attr, 162 char *buf) 163 { 164 ssize_t rc; 165 166 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t)); 167 return rc; 168 } 169 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL); 170 171 static struct attribute *crash_note_cpu_attrs[] = { 172 &dev_attr_crash_notes.attr, 173 &dev_attr_crash_notes_size.attr, 174 NULL 175 }; 176 177 static struct attribute_group crash_note_cpu_attr_group = { 178 .attrs = crash_note_cpu_attrs, 179 }; 180 #endif 181 182 static const struct attribute_group *common_cpu_attr_groups[] = { 183 #ifdef CONFIG_KEXEC 184 &crash_note_cpu_attr_group, 185 #endif 186 NULL 187 }; 188 189 static const struct attribute_group *hotplugable_cpu_attr_groups[] = { 190 #ifdef CONFIG_KEXEC 191 &crash_note_cpu_attr_group, 192 #endif 193 NULL 194 }; 195 196 /* 197 * Print cpu online, possible, present, and system maps 198 */ 199 200 struct cpu_attr { 201 struct device_attribute attr; 202 const struct cpumask *const * const map; 203 }; 204 205 static ssize_t show_cpus_attr(struct device *dev, 206 struct device_attribute *attr, 207 char *buf) 208 { 209 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr); 210 211 return cpumap_print_to_pagebuf(true, buf, *ca->map); 212 } 213 214 #define _CPU_ATTR(name, map) \ 215 { __ATTR(name, 0444, show_cpus_attr, NULL), map } 216 217 /* Keep in sync with cpu_subsys_attrs */ 218 static struct cpu_attr cpu_attrs[] = { 219 _CPU_ATTR(online, &cpu_online_mask), 220 _CPU_ATTR(possible, &cpu_possible_mask), 221 _CPU_ATTR(present, &cpu_present_mask), 222 }; 223 224 /* 225 * Print values for NR_CPUS and offlined cpus 226 */ 227 static ssize_t print_cpus_kernel_max(struct device *dev, 228 struct device_attribute *attr, char *buf) 229 { 230 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 231 return n; 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 n = 0, len = PAGE_SIZE-2; 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 n = cpulist_scnprintf(buf, len, offline); 249 free_cpumask_var(offline); 250 251 /* display offline cpus >= nr_cpu_ids */ 252 if (total_cpus && nr_cpu_ids < total_cpus) { 253 if (n && n < len) 254 buf[n++] = ','; 255 256 if (nr_cpu_ids == total_cpus-1) 257 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 258 else 259 n += snprintf(&buf[n], len - n, "%d-%d", 260 nr_cpu_ids, total_cpus-1); 261 } 262 263 n += snprintf(&buf[n], len - n, "\n"); 264 return n; 265 } 266 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 267 268 static void cpu_device_release(struct device *dev) 269 { 270 /* 271 * This is an empty function to prevent the driver core from spitting a 272 * warning at us. Yes, I know this is directly opposite of what the 273 * documentation for the driver core and kobjects say, and the author 274 * of this code has already been publically ridiculed for doing 275 * something as foolish as this. However, at this point in time, it is 276 * the only way to handle the issue of statically allocated cpu 277 * devices. The different architectures will have their cpu device 278 * code reworked to properly handle this in the near future, so this 279 * function will then be changed to correctly free up the memory held 280 * by the cpu device. 281 * 282 * Never copy this way of doing things, or you too will be made fun of 283 * on the linux-kernel list, you have been warned. 284 */ 285 } 286 287 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 288 static ssize_t print_cpu_modalias(struct device *dev, 289 struct device_attribute *attr, 290 char *buf) 291 { 292 ssize_t n; 293 u32 i; 294 295 n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:", 296 CPU_FEATURE_TYPEVAL); 297 298 for (i = 0; i < MAX_CPU_FEATURES; i++) 299 if (cpu_have_feature(i)) { 300 if (PAGE_SIZE < n + sizeof(",XXXX\n")) { 301 WARN(1, "CPU features overflow page\n"); 302 break; 303 } 304 n += sprintf(&buf[n], ",%04X", i); 305 } 306 buf[n++] = '\n'; 307 return n; 308 } 309 310 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env) 311 { 312 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); 313 if (buf) { 314 print_cpu_modalias(NULL, NULL, buf); 315 add_uevent_var(env, "MODALIAS=%s", buf); 316 kfree(buf); 317 } 318 return 0; 319 } 320 #endif 321 322 /* 323 * register_cpu - Setup a sysfs device for a CPU. 324 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 325 * sysfs for this CPU. 326 * @num - CPU number to use when creating the device. 327 * 328 * Initialize and register the CPU device. 329 */ 330 int register_cpu(struct cpu *cpu, int num) 331 { 332 int error; 333 334 cpu->node_id = cpu_to_node(num); 335 memset(&cpu->dev, 0x00, sizeof(struct device)); 336 cpu->dev.id = num; 337 cpu->dev.bus = &cpu_subsys; 338 cpu->dev.release = cpu_device_release; 339 cpu->dev.offline_disabled = !cpu->hotpluggable; 340 cpu->dev.offline = !cpu_online(num); 341 cpu->dev.of_node = of_get_cpu_node(num, NULL); 342 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 343 cpu->dev.bus->uevent = cpu_uevent; 344 #endif 345 cpu->dev.groups = common_cpu_attr_groups; 346 if (cpu->hotpluggable) 347 cpu->dev.groups = hotplugable_cpu_attr_groups; 348 error = device_register(&cpu->dev); 349 if (!error) 350 per_cpu(cpu_sys_devices, num) = &cpu->dev; 351 if (!error) 352 register_cpu_under_node(num, cpu_to_node(num)); 353 354 return error; 355 } 356 357 struct device *get_cpu_device(unsigned cpu) 358 { 359 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 360 return per_cpu(cpu_sys_devices, cpu); 361 else 362 return NULL; 363 } 364 EXPORT_SYMBOL_GPL(get_cpu_device); 365 366 static void device_create_release(struct device *dev) 367 { 368 kfree(dev); 369 } 370 371 static struct device * 372 __cpu_device_create(struct device *parent, void *drvdata, 373 const struct attribute_group **groups, 374 const char *fmt, va_list args) 375 { 376 struct device *dev = NULL; 377 int retval = -ENODEV; 378 379 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 380 if (!dev) { 381 retval = -ENOMEM; 382 goto error; 383 } 384 385 device_initialize(dev); 386 dev->parent = parent; 387 dev->groups = groups; 388 dev->release = device_create_release; 389 dev_set_drvdata(dev, drvdata); 390 391 retval = kobject_set_name_vargs(&dev->kobj, fmt, args); 392 if (retval) 393 goto error; 394 395 retval = device_add(dev); 396 if (retval) 397 goto error; 398 399 return dev; 400 401 error: 402 put_device(dev); 403 return ERR_PTR(retval); 404 } 405 406 struct device *cpu_device_create(struct device *parent, void *drvdata, 407 const struct attribute_group **groups, 408 const char *fmt, ...) 409 { 410 va_list vargs; 411 struct device *dev; 412 413 va_start(vargs, fmt); 414 dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs); 415 va_end(vargs); 416 return dev; 417 } 418 EXPORT_SYMBOL_GPL(cpu_device_create); 419 420 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 421 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL); 422 #endif 423 424 static struct attribute *cpu_root_attrs[] = { 425 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 426 &dev_attr_probe.attr, 427 &dev_attr_release.attr, 428 #endif 429 &cpu_attrs[0].attr.attr, 430 &cpu_attrs[1].attr.attr, 431 &cpu_attrs[2].attr.attr, 432 &dev_attr_kernel_max.attr, 433 &dev_attr_offline.attr, 434 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 435 &dev_attr_modalias.attr, 436 #endif 437 NULL 438 }; 439 440 static struct attribute_group cpu_root_attr_group = { 441 .attrs = cpu_root_attrs, 442 }; 443 444 static const struct attribute_group *cpu_root_attr_groups[] = { 445 &cpu_root_attr_group, 446 NULL, 447 }; 448 449 bool cpu_is_hotpluggable(unsigned cpu) 450 { 451 struct device *dev = get_cpu_device(cpu); 452 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 453 } 454 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 455 456 #ifdef CONFIG_GENERIC_CPU_DEVICES 457 static DEFINE_PER_CPU(struct cpu, cpu_devices); 458 #endif 459 460 static void __init cpu_dev_register_generic(void) 461 { 462 #ifdef CONFIG_GENERIC_CPU_DEVICES 463 int i; 464 465 for_each_possible_cpu(i) { 466 if (register_cpu(&per_cpu(cpu_devices, i), i)) 467 panic("Failed to register CPU device"); 468 } 469 #endif 470 } 471 472 void __init cpu_dev_init(void) 473 { 474 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 475 panic("Failed to register CPU subsystem"); 476 477 cpu_dev_register_generic(); 478 } 479