1 /* 2 * CPU subsystem support 3 */ 4 5 #include <linux/module.h> 6 #include <linux/init.h> 7 #include <linux/sched.h> 8 #include <linux/cpu.h> 9 #include <linux/topology.h> 10 #include <linux/device.h> 11 #include <linux/node.h> 12 #include <linux/gfp.h> 13 14 #include "base.h" 15 16 struct bus_type cpu_subsys = { 17 .name = "cpu", 18 .dev_name = "cpu", 19 }; 20 EXPORT_SYMBOL_GPL(cpu_subsys); 21 22 static DEFINE_PER_CPU(struct device *, cpu_sys_devices); 23 24 #ifdef CONFIG_HOTPLUG_CPU 25 static ssize_t show_online(struct device *dev, 26 struct device_attribute *attr, 27 char *buf) 28 { 29 struct cpu *cpu = container_of(dev, struct cpu, dev); 30 31 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id)); 32 } 33 34 static ssize_t __ref store_online(struct device *dev, 35 struct device_attribute *attr, 36 const char *buf, size_t count) 37 { 38 struct cpu *cpu = container_of(dev, struct cpu, dev); 39 ssize_t ret; 40 41 cpu_hotplug_driver_lock(); 42 switch (buf[0]) { 43 case '0': 44 ret = cpu_down(cpu->dev.id); 45 if (!ret) 46 kobject_uevent(&dev->kobj, KOBJ_OFFLINE); 47 break; 48 case '1': 49 ret = cpu_up(cpu->dev.id); 50 if (!ret) 51 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 52 break; 53 default: 54 ret = -EINVAL; 55 } 56 cpu_hotplug_driver_unlock(); 57 58 if (ret >= 0) 59 ret = count; 60 return ret; 61 } 62 static DEVICE_ATTR(online, 0644, show_online, store_online); 63 64 static void __cpuinit register_cpu_control(struct cpu *cpu) 65 { 66 device_create_file(&cpu->dev, &dev_attr_online); 67 } 68 void unregister_cpu(struct cpu *cpu) 69 { 70 int logical_cpu = cpu->dev.id; 71 72 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 73 74 device_remove_file(&cpu->dev, &dev_attr_online); 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 return arch_cpu_probe(buf, count); 88 } 89 90 static ssize_t cpu_release_store(struct device *dev, 91 struct device_attribute *attr, 92 const char *buf, 93 size_t count) 94 { 95 return arch_cpu_release(buf, count); 96 } 97 98 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); 99 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); 100 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ 101 102 #else /* ... !CONFIG_HOTPLUG_CPU */ 103 static inline void register_cpu_control(struct cpu *cpu) 104 { 105 } 106 #endif /* CONFIG_HOTPLUG_CPU */ 107 108 #ifdef CONFIG_KEXEC 109 #include <linux/kexec.h> 110 111 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr, 112 char *buf) 113 { 114 struct cpu *cpu = container_of(dev, struct cpu, dev); 115 ssize_t rc; 116 unsigned long long addr; 117 int cpunum; 118 119 cpunum = cpu->dev.id; 120 121 /* 122 * Might be reading other cpu's data based on which cpu read thread 123 * has been scheduled. But cpu data (memory) is allocated once during 124 * boot up and this data does not change there after. Hence this 125 * operation should be safe. No locking required. 126 */ 127 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); 128 rc = sprintf(buf, "%Lx\n", addr); 129 return rc; 130 } 131 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 132 #endif 133 134 /* 135 * Print cpu online, possible, present, and system maps 136 */ 137 138 struct cpu_attr { 139 struct device_attribute attr; 140 const struct cpumask *const * const map; 141 }; 142 143 static ssize_t show_cpus_attr(struct device *dev, 144 struct device_attribute *attr, 145 char *buf) 146 { 147 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr); 148 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); 149 150 buf[n++] = '\n'; 151 buf[n] = '\0'; 152 return n; 153 } 154 155 #define _CPU_ATTR(name, map) \ 156 { __ATTR(name, 0444, show_cpus_attr, NULL), map } 157 158 /* Keep in sync with cpu_subsys_attrs */ 159 static struct cpu_attr cpu_attrs[] = { 160 _CPU_ATTR(online, &cpu_online_mask), 161 _CPU_ATTR(possible, &cpu_possible_mask), 162 _CPU_ATTR(present, &cpu_present_mask), 163 }; 164 165 /* 166 * Print values for NR_CPUS and offlined cpus 167 */ 168 static ssize_t print_cpus_kernel_max(struct device *dev, 169 struct device_attribute *attr, char *buf) 170 { 171 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 172 return n; 173 } 174 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 175 176 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 177 unsigned int total_cpus; 178 179 static ssize_t print_cpus_offline(struct device *dev, 180 struct device_attribute *attr, char *buf) 181 { 182 int n = 0, len = PAGE_SIZE-2; 183 cpumask_var_t offline; 184 185 /* display offline cpus < nr_cpu_ids */ 186 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 187 return -ENOMEM; 188 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); 189 n = cpulist_scnprintf(buf, len, offline); 190 free_cpumask_var(offline); 191 192 /* display offline cpus >= nr_cpu_ids */ 193 if (total_cpus && nr_cpu_ids < total_cpus) { 194 if (n && n < len) 195 buf[n++] = ','; 196 197 if (nr_cpu_ids == total_cpus-1) 198 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 199 else 200 n += snprintf(&buf[n], len - n, "%d-%d", 201 nr_cpu_ids, total_cpus-1); 202 } 203 204 n += snprintf(&buf[n], len - n, "\n"); 205 return n; 206 } 207 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 208 209 /* 210 * register_cpu - Setup a sysfs device for a CPU. 211 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 212 * sysfs for this CPU. 213 * @num - CPU number to use when creating the device. 214 * 215 * Initialize and register the CPU device. 216 */ 217 int __cpuinit register_cpu(struct cpu *cpu, int num) 218 { 219 int error; 220 221 cpu->node_id = cpu_to_node(num); 222 cpu->dev.id = num; 223 cpu->dev.bus = &cpu_subsys; 224 error = device_register(&cpu->dev); 225 if (!error && cpu->hotpluggable) 226 register_cpu_control(cpu); 227 if (!error) 228 per_cpu(cpu_sys_devices, num) = &cpu->dev; 229 if (!error) 230 register_cpu_under_node(num, cpu_to_node(num)); 231 232 #ifdef CONFIG_KEXEC 233 if (!error) 234 error = device_create_file(&cpu->dev, &dev_attr_crash_notes); 235 #endif 236 return error; 237 } 238 239 struct device *get_cpu_device(unsigned cpu) 240 { 241 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 242 return per_cpu(cpu_sys_devices, cpu); 243 else 244 return NULL; 245 } 246 EXPORT_SYMBOL_GPL(get_cpu_device); 247 248 static struct attribute *cpu_root_attrs[] = { 249 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 250 &dev_attr_probe.attr, 251 &dev_attr_release.attr, 252 #endif 253 &cpu_attrs[0].attr.attr, 254 &cpu_attrs[1].attr.attr, 255 &cpu_attrs[2].attr.attr, 256 &dev_attr_kernel_max.attr, 257 &dev_attr_offline.attr, 258 NULL 259 }; 260 261 static struct attribute_group cpu_root_attr_group = { 262 .attrs = cpu_root_attrs, 263 }; 264 265 static const struct attribute_group *cpu_root_attr_groups[] = { 266 &cpu_root_attr_group, 267 NULL, 268 }; 269 270 int __init cpu_dev_init(void) 271 { 272 int err; 273 274 err = subsys_system_register(&cpu_subsys, cpu_root_attr_groups); 275 if (err) 276 return err; 277 278 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 279 err = sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root); 280 #endif 281 return err; 282 } 283