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