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/percpu.h> 15 16 #include "base.h" 17 18 struct bus_type cpu_subsys = { 19 .name = "cpu", 20 .dev_name = "cpu", 21 }; 22 EXPORT_SYMBOL_GPL(cpu_subsys); 23 24 static DEFINE_PER_CPU(struct device *, cpu_sys_devices); 25 26 #ifdef CONFIG_HOTPLUG_CPU 27 static ssize_t show_online(struct device *dev, 28 struct device_attribute *attr, 29 char *buf) 30 { 31 struct cpu *cpu = container_of(dev, struct cpu, dev); 32 33 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id)); 34 } 35 36 static ssize_t __ref store_online(struct device *dev, 37 struct device_attribute *attr, 38 const char *buf, size_t count) 39 { 40 struct cpu *cpu = container_of(dev, struct cpu, dev); 41 ssize_t ret; 42 43 cpu_hotplug_driver_lock(); 44 switch (buf[0]) { 45 case '0': 46 ret = cpu_down(cpu->dev.id); 47 if (!ret) 48 kobject_uevent(&dev->kobj, KOBJ_OFFLINE); 49 break; 50 case '1': 51 ret = cpu_up(cpu->dev.id); 52 if (!ret) 53 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 54 break; 55 default: 56 ret = -EINVAL; 57 } 58 cpu_hotplug_driver_unlock(); 59 60 if (ret >= 0) 61 ret = count; 62 return ret; 63 } 64 static DEVICE_ATTR(online, 0644, show_online, store_online); 65 66 static void __cpuinit register_cpu_control(struct cpu *cpu) 67 { 68 device_create_file(&cpu->dev, &dev_attr_online); 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_remove_file(&cpu->dev, &dev_attr_online); 77 78 device_unregister(&cpu->dev); 79 per_cpu(cpu_sys_devices, logical_cpu) = NULL; 80 return; 81 } 82 83 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 84 static ssize_t cpu_probe_store(struct device *dev, 85 struct device_attribute *attr, 86 const char *buf, 87 size_t count) 88 { 89 return arch_cpu_probe(buf, count); 90 } 91 92 static ssize_t cpu_release_store(struct device *dev, 93 struct device_attribute *attr, 94 const char *buf, 95 size_t count) 96 { 97 return arch_cpu_release(buf, count); 98 } 99 100 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); 101 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); 102 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ 103 104 #else /* ... !CONFIG_HOTPLUG_CPU */ 105 static inline void register_cpu_control(struct cpu *cpu) 106 { 107 } 108 #endif /* CONFIG_HOTPLUG_CPU */ 109 110 #ifdef CONFIG_KEXEC 111 #include <linux/kexec.h> 112 113 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr, 114 char *buf) 115 { 116 struct cpu *cpu = container_of(dev, struct cpu, dev); 117 ssize_t rc; 118 unsigned long long addr; 119 int cpunum; 120 121 cpunum = cpu->dev.id; 122 123 /* 124 * Might be reading other cpu's data based on which cpu read thread 125 * has been scheduled. But cpu data (memory) is allocated once during 126 * boot up and this data does not change there after. Hence this 127 * operation should be safe. No locking required. 128 */ 129 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); 130 rc = sprintf(buf, "%Lx\n", addr); 131 return rc; 132 } 133 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 134 #endif 135 136 /* 137 * Print cpu online, possible, present, and system maps 138 */ 139 140 struct cpu_attr { 141 struct device_attribute attr; 142 const struct cpumask *const * const map; 143 }; 144 145 static ssize_t show_cpus_attr(struct device *dev, 146 struct device_attribute *attr, 147 char *buf) 148 { 149 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr); 150 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); 151 152 buf[n++] = '\n'; 153 buf[n] = '\0'; 154 return n; 155 } 156 157 #define _CPU_ATTR(name, map) \ 158 { __ATTR(name, 0444, show_cpus_attr, NULL), map } 159 160 /* Keep in sync with cpu_subsys_attrs */ 161 static struct cpu_attr cpu_attrs[] = { 162 _CPU_ATTR(online, &cpu_online_mask), 163 _CPU_ATTR(possible, &cpu_possible_mask), 164 _CPU_ATTR(present, &cpu_present_mask), 165 }; 166 167 /* 168 * Print values for NR_CPUS and offlined cpus 169 */ 170 static ssize_t print_cpus_kernel_max(struct device *dev, 171 struct device_attribute *attr, char *buf) 172 { 173 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 174 return n; 175 } 176 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 177 178 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 179 unsigned int total_cpus; 180 181 static ssize_t print_cpus_offline(struct device *dev, 182 struct device_attribute *attr, char *buf) 183 { 184 int n = 0, len = PAGE_SIZE-2; 185 cpumask_var_t offline; 186 187 /* display offline cpus < nr_cpu_ids */ 188 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 189 return -ENOMEM; 190 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); 191 n = cpulist_scnprintf(buf, len, offline); 192 free_cpumask_var(offline); 193 194 /* display offline cpus >= nr_cpu_ids */ 195 if (total_cpus && nr_cpu_ids < total_cpus) { 196 if (n && n < len) 197 buf[n++] = ','; 198 199 if (nr_cpu_ids == total_cpus-1) 200 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 201 else 202 n += snprintf(&buf[n], len - n, "%d-%d", 203 nr_cpu_ids, total_cpus-1); 204 } 205 206 n += snprintf(&buf[n], len - n, "\n"); 207 return n; 208 } 209 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 210 211 static void cpu_device_release(struct device *dev) 212 { 213 /* 214 * This is an empty function to prevent the driver core from spitting a 215 * warning at us. Yes, I know this is directly opposite of what the 216 * documentation for the driver core and kobjects say, and the author 217 * of this code has already been publically ridiculed for doing 218 * something as foolish as this. However, at this point in time, it is 219 * the only way to handle the issue of statically allocated cpu 220 * devices. The different architectures will have their cpu device 221 * code reworked to properly handle this in the near future, so this 222 * function will then be changed to correctly free up the memory held 223 * by the cpu device. 224 * 225 * Never copy this way of doing things, or you too will be made fun of 226 * on the linux-kerenl list, you have been warned. 227 */ 228 } 229 230 /* 231 * register_cpu - Setup a sysfs device for a CPU. 232 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 233 * sysfs for this CPU. 234 * @num - CPU number to use when creating the device. 235 * 236 * Initialize and register the CPU device. 237 */ 238 int __cpuinit register_cpu(struct cpu *cpu, int num) 239 { 240 int error; 241 242 cpu->node_id = cpu_to_node(num); 243 cpu->dev.id = num; 244 cpu->dev.bus = &cpu_subsys; 245 cpu->dev.release = cpu_device_release; 246 error = device_register(&cpu->dev); 247 if (!error && cpu->hotpluggable) 248 register_cpu_control(cpu); 249 if (!error) 250 per_cpu(cpu_sys_devices, num) = &cpu->dev; 251 if (!error) 252 register_cpu_under_node(num, cpu_to_node(num)); 253 254 #ifdef CONFIG_KEXEC 255 if (!error) 256 error = device_create_file(&cpu->dev, &dev_attr_crash_notes); 257 #endif 258 return error; 259 } 260 261 struct device *get_cpu_device(unsigned cpu) 262 { 263 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 264 return per_cpu(cpu_sys_devices, cpu); 265 else 266 return NULL; 267 } 268 EXPORT_SYMBOL_GPL(get_cpu_device); 269 270 static struct attribute *cpu_root_attrs[] = { 271 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 272 &dev_attr_probe.attr, 273 &dev_attr_release.attr, 274 #endif 275 &cpu_attrs[0].attr.attr, 276 &cpu_attrs[1].attr.attr, 277 &cpu_attrs[2].attr.attr, 278 &dev_attr_kernel_max.attr, 279 &dev_attr_offline.attr, 280 NULL 281 }; 282 283 static struct attribute_group cpu_root_attr_group = { 284 .attrs = cpu_root_attrs, 285 }; 286 287 static const struct attribute_group *cpu_root_attr_groups[] = { 288 &cpu_root_attr_group, 289 NULL, 290 }; 291 292 bool cpu_is_hotpluggable(unsigned cpu) 293 { 294 struct device *dev = get_cpu_device(cpu); 295 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 296 } 297 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 298 299 #ifdef CONFIG_GENERIC_CPU_DEVICES 300 static DEFINE_PER_CPU(struct cpu, cpu_devices); 301 #endif 302 303 static void __init cpu_dev_register_generic(void) 304 { 305 #ifdef CONFIG_GENERIC_CPU_DEVICES 306 int i; 307 308 for_each_possible_cpu(i) { 309 if (register_cpu(&per_cpu(cpu_devices, i), i)) 310 panic("Failed to register CPU device"); 311 } 312 #endif 313 } 314 315 void __init cpu_dev_init(void) 316 { 317 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 318 panic("Failed to register CPU subsystem"); 319 320 cpu_dev_register_generic(); 321 322 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 323 sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root); 324 #endif 325 } 326