drivers/base/cpu.c

   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 }