cpu.c revision 29bb5d4fd3140a7d5d02d858118c74a45f15c296
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 18struct bus_type cpu_subsys = { 19 .name = "cpu", 20 .dev_name = "cpu", 21}; 22EXPORT_SYMBOL_GPL(cpu_subsys); 23 24static DEFINE_PER_CPU(struct device *, cpu_sys_devices); 25 26#ifdef CONFIG_HOTPLUG_CPU 27static 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 36static 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} 64static DEVICE_ATTR(online, 0644, show_online, store_online); 65 66static void __cpuinit register_cpu_control(struct cpu *cpu) 67{ 68 device_create_file(&cpu->dev, &dev_attr_online); 69} 70void 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 84static 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 92static 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 100static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); 101static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); 102#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ 103 104#else /* ... !CONFIG_HOTPLUG_CPU */ 105static 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 113static 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} 133static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 134#endif 135 136/* 137 * Print cpu online, possible, present, and system maps 138 */ 139 140struct cpu_attr { 141 struct device_attribute attr; 142 const struct cpumask *const * const map; 143}; 144 145static 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 */ 161static 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 */ 170static 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} 176static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 177 178/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 179unsigned int total_cpus; 180 181static 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} 209static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 210 211static 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 */ 238int __cpuinit register_cpu(struct cpu *cpu, int num) 239{ 240 int error; 241 242 cpu->node_id = cpu_to_node(num); 243 memset(&cpu->dev, 0x00, sizeof(struct device)); 244 cpu->dev.id = num; 245 cpu->dev.bus = &cpu_subsys; 246 cpu->dev.release = cpu_device_release; 247 error = device_register(&cpu->dev); 248 if (!error && cpu->hotpluggable) 249 register_cpu_control(cpu); 250 if (!error) 251 per_cpu(cpu_sys_devices, num) = &cpu->dev; 252 if (!error) 253 register_cpu_under_node(num, cpu_to_node(num)); 254 255#ifdef CONFIG_KEXEC 256 if (!error) 257 error = device_create_file(&cpu->dev, &dev_attr_crash_notes); 258#endif 259 return error; 260} 261 262struct device *get_cpu_device(unsigned cpu) 263{ 264 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 265 return per_cpu(cpu_sys_devices, cpu); 266 else 267 return NULL; 268} 269EXPORT_SYMBOL_GPL(get_cpu_device); 270 271static struct attribute *cpu_root_attrs[] = { 272#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 273 &dev_attr_probe.attr, 274 &dev_attr_release.attr, 275#endif 276 &cpu_attrs[0].attr.attr, 277 &cpu_attrs[1].attr.attr, 278 &cpu_attrs[2].attr.attr, 279 &dev_attr_kernel_max.attr, 280 &dev_attr_offline.attr, 281 NULL 282}; 283 284static struct attribute_group cpu_root_attr_group = { 285 .attrs = cpu_root_attrs, 286}; 287 288static const struct attribute_group *cpu_root_attr_groups[] = { 289 &cpu_root_attr_group, 290 NULL, 291}; 292 293bool cpu_is_hotpluggable(unsigned cpu) 294{ 295 struct device *dev = get_cpu_device(cpu); 296 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 297} 298EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 299 300#ifdef CONFIG_GENERIC_CPU_DEVICES 301static DEFINE_PER_CPU(struct cpu, cpu_devices); 302#endif 303 304static void __init cpu_dev_register_generic(void) 305{ 306#ifdef CONFIG_GENERIC_CPU_DEVICES 307 int i; 308 309 for_each_possible_cpu(i) { 310 if (register_cpu(&per_cpu(cpu_devices, i), i)) 311 panic("Failed to register CPU device"); 312 } 313#endif 314} 315 316void __init cpu_dev_init(void) 317{ 318 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 319 panic("Failed to register CPU subsystem"); 320 321 cpu_dev_register_generic(); 322 323#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 324 sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root); 325#endif 326} 327