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 19 #include "base.h" 20 21 static DEFINE_PER_CPU(struct device *, cpu_sys_devices); 22 23 static int cpu_subsys_match(struct device *dev, struct device_driver *drv) 24 { 25 /* ACPI style match is the only one that may succeed. */ 26 if (acpi_driver_match_device(dev, drv)) 27 return 1; 28 29 return 0; 30 } 31 32 #ifdef CONFIG_HOTPLUG_CPU 33 static void change_cpu_under_node(struct cpu *cpu, 34 unsigned int from_nid, unsigned int to_nid) 35 { 36 int cpuid = cpu->dev.id; 37 unregister_cpu_under_node(cpuid, from_nid); 38 register_cpu_under_node(cpuid, to_nid); 39 cpu->node_id = to_nid; 40 } 41 42 static int __ref cpu_subsys_online(struct device *dev) 43 { 44 struct cpu *cpu = container_of(dev, struct cpu, dev); 45 int cpuid = dev->id; 46 int from_nid, to_nid; 47 int ret; 48 49 from_nid = cpu_to_node(cpuid); 50 if (from_nid == NUMA_NO_NODE) 51 return -ENODEV; 52 53 ret = cpu_up(cpuid); 54 /* 55 * When hot adding memory to memoryless node and enabling a cpu 56 * on the node, node number of the cpu may internally change. 57 */ 58 to_nid = cpu_to_node(cpuid); 59 if (from_nid != to_nid) 60 change_cpu_under_node(cpu, from_nid, to_nid); 61 62 return ret; 63 } 64 65 static int cpu_subsys_offline(struct device *dev) 66 { 67 return cpu_down(dev->id); 68 } 69 70 void unregister_cpu(struct cpu *cpu) 71 { 72 int logical_cpu = cpu->dev.id; 73 74 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 75 76 device_unregister(&cpu->dev); 77 per_cpu(cpu_sys_devices, logical_cpu) = NULL; 78 return; 79 } 80 81 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 82 static ssize_t cpu_probe_store(struct device *dev, 83 struct device_attribute *attr, 84 const char *buf, 85 size_t count) 86 { 87 ssize_t cnt; 88 int ret; 89 90 ret = lock_device_hotplug_sysfs(); 91 if (ret) 92 return ret; 93 94 cnt = arch_cpu_probe(buf, count); 95 96 unlock_device_hotplug(); 97 return cnt; 98 } 99 100 static ssize_t cpu_release_store(struct device *dev, 101 struct device_attribute *attr, 102 const char *buf, 103 size_t count) 104 { 105 ssize_t cnt; 106 int ret; 107 108 ret = lock_device_hotplug_sysfs(); 109 if (ret) 110 return ret; 111 112 cnt = arch_cpu_release(buf, count); 113 114 unlock_device_hotplug(); 115 return cnt; 116 } 117 118 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); 119 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); 120 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ 121 #endif /* CONFIG_HOTPLUG_CPU */ 122 123 struct bus_type cpu_subsys = { 124 .name = "cpu", 125 .dev_name = "cpu", 126 .match = cpu_subsys_match, 127 #ifdef CONFIG_HOTPLUG_CPU 128 .online = cpu_subsys_online, 129 .offline = cpu_subsys_offline, 130 #endif 131 }; 132 EXPORT_SYMBOL_GPL(cpu_subsys); 133 134 #ifdef CONFIG_KEXEC 135 #include <linux/kexec.h> 136 137 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr, 138 char *buf) 139 { 140 struct cpu *cpu = container_of(dev, struct cpu, dev); 141 ssize_t rc; 142 unsigned long long addr; 143 int cpunum; 144 145 cpunum = cpu->dev.id; 146 147 /* 148 * Might be reading other cpu's data based on which cpu read thread 149 * has been scheduled. But cpu data (memory) is allocated once during 150 * boot up and this data does not change there after. Hence this 151 * operation should be safe. No locking required. 152 */ 153 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); 154 rc = sprintf(buf, "%Lx\n", addr); 155 return rc; 156 } 157 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 158 159 static ssize_t show_crash_notes_size(struct device *dev, 160 struct device_attribute *attr, 161 char *buf) 162 { 163 ssize_t rc; 164 165 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t)); 166 return rc; 167 } 168 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL); 169 170 static struct attribute *crash_note_cpu_attrs[] = { 171 &dev_attr_crash_notes.attr, 172 &dev_attr_crash_notes_size.attr, 173 NULL 174 }; 175 176 static struct attribute_group crash_note_cpu_attr_group = { 177 .attrs = crash_note_cpu_attrs, 178 }; 179 #endif 180 181 static const struct attribute_group *common_cpu_attr_groups[] = { 182 #ifdef CONFIG_KEXEC 183 &crash_note_cpu_attr_group, 184 #endif 185 NULL 186 }; 187 188 static const struct attribute_group *hotplugable_cpu_attr_groups[] = { 189 #ifdef CONFIG_KEXEC 190 &crash_note_cpu_attr_group, 191 #endif 192 NULL 193 }; 194 195 /* 196 * Print cpu online, possible, present, and system maps 197 */ 198 199 struct cpu_attr { 200 struct device_attribute attr; 201 const struct cpumask *const * const map; 202 }; 203 204 static ssize_t show_cpus_attr(struct device *dev, 205 struct device_attribute *attr, 206 char *buf) 207 { 208 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr); 209 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); 210 211 buf[n++] = '\n'; 212 buf[n] = '\0'; 213 return n; 214 } 215 216 #define _CPU_ATTR(name, map) \ 217 { __ATTR(name, 0444, show_cpus_attr, NULL), map } 218 219 /* Keep in sync with cpu_subsys_attrs */ 220 static struct cpu_attr cpu_attrs[] = { 221 _CPU_ATTR(online, &cpu_online_mask), 222 _CPU_ATTR(possible, &cpu_possible_mask), 223 _CPU_ATTR(present, &cpu_present_mask), 224 }; 225 226 /* 227 * Print values for NR_CPUS and offlined cpus 228 */ 229 static ssize_t print_cpus_kernel_max(struct device *dev, 230 struct device_attribute *attr, char *buf) 231 { 232 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 233 return n; 234 } 235 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 236 237 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 238 unsigned int total_cpus; 239 240 static ssize_t print_cpus_offline(struct device *dev, 241 struct device_attribute *attr, char *buf) 242 { 243 int n = 0, len = PAGE_SIZE-2; 244 cpumask_var_t offline; 245 246 /* display offline cpus < nr_cpu_ids */ 247 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 248 return -ENOMEM; 249 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); 250 n = cpulist_scnprintf(buf, len, offline); 251 free_cpumask_var(offline); 252 253 /* display offline cpus >= nr_cpu_ids */ 254 if (total_cpus && nr_cpu_ids < total_cpus) { 255 if (n && n < len) 256 buf[n++] = ','; 257 258 if (nr_cpu_ids == total_cpus-1) 259 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 260 else 261 n += snprintf(&buf[n], len - n, "%d-%d", 262 nr_cpu_ids, total_cpus-1); 263 } 264 265 n += snprintf(&buf[n], len - n, "\n"); 266 return n; 267 } 268 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 269 270 static void cpu_device_release(struct device *dev) 271 { 272 /* 273 * This is an empty function to prevent the driver core from spitting a 274 * warning at us. Yes, I know this is directly opposite of what the 275 * documentation for the driver core and kobjects say, and the author 276 * of this code has already been publically ridiculed for doing 277 * something as foolish as this. However, at this point in time, it is 278 * the only way to handle the issue of statically allocated cpu 279 * devices. The different architectures will have their cpu device 280 * code reworked to properly handle this in the near future, so this 281 * function will then be changed to correctly free up the memory held 282 * by the cpu device. 283 * 284 * Never copy this way of doing things, or you too will be made fun of 285 * on the linux-kernel list, you have been warned. 286 */ 287 } 288 289 /* 290 * register_cpu - Setup a sysfs device for a CPU. 291 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 292 * sysfs for this CPU. 293 * @num - CPU number to use when creating the device. 294 * 295 * Initialize and register the CPU device. 296 */ 297 int register_cpu(struct cpu *cpu, int num) 298 { 299 int error; 300 301 cpu->node_id = cpu_to_node(num); 302 memset(&cpu->dev, 0x00, sizeof(struct device)); 303 cpu->dev.id = num; 304 cpu->dev.bus = &cpu_subsys; 305 cpu->dev.release = cpu_device_release; 306 cpu->dev.offline_disabled = !cpu->hotpluggable; 307 cpu->dev.offline = !cpu_online(num); 308 cpu->dev.of_node = of_get_cpu_node(num, NULL); 309 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE 310 cpu->dev.bus->uevent = arch_cpu_uevent; 311 #endif 312 cpu->dev.groups = common_cpu_attr_groups; 313 if (cpu->hotpluggable) 314 cpu->dev.groups = hotplugable_cpu_attr_groups; 315 error = device_register(&cpu->dev); 316 if (!error) 317 per_cpu(cpu_sys_devices, num) = &cpu->dev; 318 if (!error) 319 register_cpu_under_node(num, cpu_to_node(num)); 320 321 return error; 322 } 323 324 struct device *get_cpu_device(unsigned cpu) 325 { 326 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 327 return per_cpu(cpu_sys_devices, cpu); 328 else 329 return NULL; 330 } 331 EXPORT_SYMBOL_GPL(get_cpu_device); 332 333 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE 334 static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL); 335 #endif 336 337 static struct attribute *cpu_root_attrs[] = { 338 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 339 &dev_attr_probe.attr, 340 &dev_attr_release.attr, 341 #endif 342 &cpu_attrs[0].attr.attr, 343 &cpu_attrs[1].attr.attr, 344 &cpu_attrs[2].attr.attr, 345 &dev_attr_kernel_max.attr, 346 &dev_attr_offline.attr, 347 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE 348 &dev_attr_modalias.attr, 349 #endif 350 NULL 351 }; 352 353 static struct attribute_group cpu_root_attr_group = { 354 .attrs = cpu_root_attrs, 355 }; 356 357 static const struct attribute_group *cpu_root_attr_groups[] = { 358 &cpu_root_attr_group, 359 NULL, 360 }; 361 362 bool cpu_is_hotpluggable(unsigned cpu) 363 { 364 struct device *dev = get_cpu_device(cpu); 365 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 366 } 367 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 368 369 #ifdef CONFIG_GENERIC_CPU_DEVICES 370 static DEFINE_PER_CPU(struct cpu, cpu_devices); 371 #endif 372 373 static void __init cpu_dev_register_generic(void) 374 { 375 #ifdef CONFIG_GENERIC_CPU_DEVICES 376 int i; 377 378 for_each_possible_cpu(i) { 379 if (register_cpu(&per_cpu(cpu_devices, i), i)) 380 panic("Failed to register CPU device"); 381 } 382 #endif 383 } 384 385 void __init cpu_dev_init(void) 386 { 387 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 388 panic("Failed to register CPU subsystem"); 389 390 cpu_dev_register_generic(); 391 } 392