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 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); 211 212 buf[n++] = '\n'; 213 buf[n] = '\0'; 214 return n; 215 } 216 217 #define _CPU_ATTR(name, map) \ 218 { __ATTR(name, 0444, show_cpus_attr, NULL), map } 219 220 /* Keep in sync with cpu_subsys_attrs */ 221 static struct cpu_attr cpu_attrs[] = { 222 _CPU_ATTR(online, &cpu_online_mask), 223 _CPU_ATTR(possible, &cpu_possible_mask), 224 _CPU_ATTR(present, &cpu_present_mask), 225 }; 226 227 /* 228 * Print values for NR_CPUS and offlined cpus 229 */ 230 static ssize_t print_cpus_kernel_max(struct device *dev, 231 struct device_attribute *attr, char *buf) 232 { 233 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 234 return n; 235 } 236 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 237 238 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 239 unsigned int total_cpus; 240 241 static ssize_t print_cpus_offline(struct device *dev, 242 struct device_attribute *attr, char *buf) 243 { 244 int n = 0, len = PAGE_SIZE-2; 245 cpumask_var_t offline; 246 247 /* display offline cpus < nr_cpu_ids */ 248 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 249 return -ENOMEM; 250 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); 251 n = cpulist_scnprintf(buf, len, offline); 252 free_cpumask_var(offline); 253 254 /* display offline cpus >= nr_cpu_ids */ 255 if (total_cpus && nr_cpu_ids < total_cpus) { 256 if (n && n < len) 257 buf[n++] = ','; 258 259 if (nr_cpu_ids == total_cpus-1) 260 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 261 else 262 n += snprintf(&buf[n], len - n, "%d-%d", 263 nr_cpu_ids, total_cpus-1); 264 } 265 266 n += snprintf(&buf[n], len - n, "\n"); 267 return n; 268 } 269 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 270 271 static void cpu_device_release(struct device *dev) 272 { 273 /* 274 * This is an empty function to prevent the driver core from spitting a 275 * warning at us. Yes, I know this is directly opposite of what the 276 * documentation for the driver core and kobjects say, and the author 277 * of this code has already been publically ridiculed for doing 278 * something as foolish as this. However, at this point in time, it is 279 * the only way to handle the issue of statically allocated cpu 280 * devices. The different architectures will have their cpu device 281 * code reworked to properly handle this in the near future, so this 282 * function will then be changed to correctly free up the memory held 283 * by the cpu device. 284 * 285 * Never copy this way of doing things, or you too will be made fun of 286 * on the linux-kernel list, you have been warned. 287 */ 288 } 289 290 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 291 static ssize_t print_cpu_modalias(struct device *dev, 292 struct device_attribute *attr, 293 char *buf) 294 { 295 ssize_t n; 296 u32 i; 297 298 n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:", 299 CPU_FEATURE_TYPEVAL); 300 301 for (i = 0; i < MAX_CPU_FEATURES; i++) 302 if (cpu_have_feature(i)) { 303 if (PAGE_SIZE < n + sizeof(",XXXX\n")) { 304 WARN(1, "CPU features overflow page\n"); 305 break; 306 } 307 n += sprintf(&buf[n], ",%04X", i); 308 } 309 buf[n++] = '\n'; 310 return n; 311 } 312 313 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env) 314 { 315 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); 316 if (buf) { 317 print_cpu_modalias(NULL, NULL, buf); 318 add_uevent_var(env, "MODALIAS=%s", buf); 319 kfree(buf); 320 } 321 return 0; 322 } 323 #endif 324 325 /* 326 * register_cpu - Setup a sysfs device for a CPU. 327 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 328 * sysfs for this CPU. 329 * @num - CPU number to use when creating the device. 330 * 331 * Initialize and register the CPU device. 332 */ 333 int register_cpu(struct cpu *cpu, int num) 334 { 335 int error; 336 337 cpu->node_id = cpu_to_node(num); 338 memset(&cpu->dev, 0x00, sizeof(struct device)); 339 cpu->dev.id = num; 340 cpu->dev.bus = &cpu_subsys; 341 cpu->dev.release = cpu_device_release; 342 cpu->dev.offline_disabled = !cpu->hotpluggable; 343 cpu->dev.offline = !cpu_online(num); 344 cpu->dev.of_node = of_get_cpu_node(num, NULL); 345 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 346 cpu->dev.bus->uevent = cpu_uevent; 347 #endif 348 cpu->dev.groups = common_cpu_attr_groups; 349 if (cpu->hotpluggable) 350 cpu->dev.groups = hotplugable_cpu_attr_groups; 351 error = device_register(&cpu->dev); 352 if (!error) 353 per_cpu(cpu_sys_devices, num) = &cpu->dev; 354 if (!error) 355 register_cpu_under_node(num, cpu_to_node(num)); 356 357 return error; 358 } 359 360 struct device *get_cpu_device(unsigned cpu) 361 { 362 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 363 return per_cpu(cpu_sys_devices, cpu); 364 else 365 return NULL; 366 } 367 EXPORT_SYMBOL_GPL(get_cpu_device); 368 369 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 370 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL); 371 #endif 372 373 static struct attribute *cpu_root_attrs[] = { 374 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 375 &dev_attr_probe.attr, 376 &dev_attr_release.attr, 377 #endif 378 &cpu_attrs[0].attr.attr, 379 &cpu_attrs[1].attr.attr, 380 &cpu_attrs[2].attr.attr, 381 &dev_attr_kernel_max.attr, 382 &dev_attr_offline.attr, 383 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE 384 &dev_attr_modalias.attr, 385 #endif 386 NULL 387 }; 388 389 static struct attribute_group cpu_root_attr_group = { 390 .attrs = cpu_root_attrs, 391 }; 392 393 static const struct attribute_group *cpu_root_attr_groups[] = { 394 &cpu_root_attr_group, 395 NULL, 396 }; 397 398 bool cpu_is_hotpluggable(unsigned cpu) 399 { 400 struct device *dev = get_cpu_device(cpu); 401 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 402 } 403 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 404 405 #ifdef CONFIG_GENERIC_CPU_DEVICES 406 static DEFINE_PER_CPU(struct cpu, cpu_devices); 407 #endif 408 409 static void __init cpu_dev_register_generic(void) 410 { 411 #ifdef CONFIG_GENERIC_CPU_DEVICES 412 int i; 413 414 for_each_possible_cpu(i) { 415 if (register_cpu(&per_cpu(cpu_devices, i), i)) 416 panic("Failed to register CPU device"); 417 } 418 #endif 419 } 420 421 void __init cpu_dev_init(void) 422 { 423 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 424 panic("Failed to register CPU subsystem"); 425 426 cpu_dev_register_generic(); 427 } 428