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 #include <linux/cpufeature.h>
  19
  20 #include "base.h"
  21
  22 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
  23
  24 static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
  25 {
  26         /* ACPI style match is the only one that may succeed. */
  27         if (acpi_driver_match_device(dev, drv))
  28                 return 1;
  29
  30         return 0;
  31 }
  32
  33 #ifdef CONFIG_HOTPLUG_CPU
  34 static void change_cpu_under_node(struct cpu *cpu,
  35                         unsigned int from_nid, unsigned int to_nid)
  36 {
  37         int cpuid = cpu->dev.id;
  38         unregister_cpu_under_node(cpuid, from_nid);
  39         register_cpu_under_node(cpuid, to_nid);
  40         cpu->node_id = to_nid;
  41 }
  42
  43 static int __ref cpu_subsys_online(struct device *dev)
  44 {
  45         struct cpu *cpu = container_of(dev, struct cpu, dev);
  46         int cpuid = dev->id;
  47         int from_nid, to_nid;
  48         int ret;
  49
  50         from_nid = cpu_to_node(cpuid);
  51         if (from_nid == NUMA_NO_NODE)
  52                 return -ENODEV;
  53
  54         ret = cpu_up(cpuid);
  55         /*
  56          * When hot adding memory to memoryless node and enabling a cpu
  57          * on the node, node number of the cpu may internally change.
  58          */
  59         to_nid = cpu_to_node(cpuid);
  60         if (from_nid != to_nid)
  61                 change_cpu_under_node(cpu, from_nid, to_nid);
  62
  63         return ret;
  64 }
  65
  66 static int cpu_subsys_offline(struct device *dev)
  67 {
  68         return cpu_down(dev->id);
  69 }
  70
  71 void unregister_cpu(struct cpu *cpu)
  72 {
  73         int logical_cpu = cpu->dev.id;
  74
  75         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
  76
  77         device_unregister(&cpu->dev);
  78         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
  79         return;
  80 }
  81
  82 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  83 static ssize_t cpu_probe_store(struct device *dev,
  84                                struct device_attribute *attr,
  85                                const char *buf,
  86                                size_t count)
  87 {
  88         ssize_t cnt;
  89         int ret;
  90
  91         ret = lock_device_hotplug_sysfs();
  92         if (ret)
  93                 return ret;
  94
  95         cnt = arch_cpu_probe(buf, count);
  96
  97         unlock_device_hotplug();
  98         return cnt;
  99 }
 100
 101 static ssize_t cpu_release_store(struct device *dev,
 102                                  struct device_attribute *attr,
 103                                  const char *buf,
 104                                  size_t count)
 105 {
 106         ssize_t cnt;
 107         int ret;
 108
 109         ret = lock_device_hotplug_sysfs();
 110         if (ret)
 111                 return ret;
 112
 113         cnt = arch_cpu_release(buf, count);
 114
 115         unlock_device_hotplug();
 116         return cnt;
 117 }
 118
 119 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
 120 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
 121 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 122 #endif /* CONFIG_HOTPLUG_CPU */
 123
 124 struct bus_type cpu_subsys = {
 125         .name = "cpu",
 126         .dev_name = "cpu",
 127         .match = cpu_subsys_match,
 128 #ifdef CONFIG_HOTPLUG_CPU
 129         .online = cpu_subsys_online,
 130         .offline = cpu_subsys_offline,
 131 #endif
 132 };
 133 EXPORT_SYMBOL_GPL(cpu_subsys);
 134
 135 #ifdef CONFIG_KEXEC
 136 #include <linux/kexec.h>
 137
 138 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
 139                                 char *buf)
 140 {
 141         struct cpu *cpu = container_of(dev, struct cpu, dev);
 142         ssize_t rc;
 143         unsigned long long addr;
 144         int cpunum;
 145
 146         cpunum = cpu->dev.id;
 147
 148         /*
 149          * Might be reading other cpu's data based on which cpu read thread
 150          * has been scheduled. But cpu data (memory) is allocated once during
 151          * boot up and this data does not change there after. Hence this
 152          * operation should be safe. No locking required.
 153          */
 154         addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
 155         rc = sprintf(buf, "%Lx\n", addr);
 156         return rc;
 157 }
 158 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 159
 160 static ssize_t show_crash_notes_size(struct device *dev,
 161                                      struct device_attribute *attr,
 162                                      char *buf)
 163 {
 164         ssize_t rc;
 165
 166         rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
 167         return rc;
 168 }
 169 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
 170
 171 static struct attribute *crash_note_cpu_attrs[] = {
 172         &dev_attr_crash_notes.attr,
 173         &dev_attr_crash_notes_size.attr,
 174         NULL
 175 };
 176
 177 static struct attribute_group crash_note_cpu_attr_group = {
 178         .attrs = crash_note_cpu_attrs,
 179 };
 180 #endif
 181
 182 static const struct attribute_group *common_cpu_attr_groups[] = {
 183 #ifdef CONFIG_KEXEC
 184         &crash_note_cpu_attr_group,
 185 #endif
 186         NULL
 187 };
 188
 189 static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
 190 #ifdef CONFIG_KEXEC
 191         &crash_note_cpu_attr_group,
 192 #endif
 193         NULL
 194 };
 195
 196 /*
 197  * Print cpu online, possible, present, and system maps
 198  */
 199
 200 struct cpu_attr {
 201         struct device_attribute attr;
 202         const struct cpumask *const * const map;
 203 };
 204
 205 static ssize_t show_cpus_attr(struct device *dev,
 206                               struct device_attribute *attr,
 207                               char *buf)
 208 {
 209         struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
 210         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
 211
 212         buf[n++] = '\n';
 213         buf[n] = '\0';
 214         return n;
 215 }
 216
 217 #define _CPU_ATTR(name, map) \
 218         { __ATTR(name, 0444, show_cpus_attr, NULL), map }
 219
 220 /* Keep in sync with cpu_subsys_attrs */
 221 static struct cpu_attr cpu_attrs[] = {
 222         _CPU_ATTR(online, &cpu_online_mask),
 223         _CPU_ATTR(possible, &cpu_possible_mask),
 224         _CPU_ATTR(present, &cpu_present_mask),
 225 };
 226
 227 /*
 228  * Print values for NR_CPUS and offlined cpus
 229  */
 230 static ssize_t print_cpus_kernel_max(struct device *dev,
 231                                      struct device_attribute *attr, char *buf)
 232 {
 233         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
 234         return n;
 235 }
 236 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
 237
 238 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
 239 unsigned int total_cpus;
 240
 241 static ssize_t print_cpus_offline(struct device *dev,
 242                                   struct device_attribute *attr, char *buf)
 243 {
 244         int n = 0, len = PAGE_SIZE-2;
 245         cpumask_var_t offline;
 246
 247         /* display offline cpus < nr_cpu_ids */
 248         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
 249                 return -ENOMEM;
 250         cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
 251         n = cpulist_scnprintf(buf, len, offline);
 252         free_cpumask_var(offline);
 253
 254         /* display offline cpus >= nr_cpu_ids */
 255         if (total_cpus && nr_cpu_ids < total_cpus) {
 256                 if (n && n < len)
 257                         buf[n++] = ',';
 258
 259                 if (nr_cpu_ids == total_cpus-1)
 260                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
 261                 else
 262                         n += snprintf(&buf[n], len - n, "%d-%d",
 263                                                       nr_cpu_ids, total_cpus-1);
 264         }
 265
 266         n += snprintf(&buf[n], len - n, "\n");
 267         return n;
 268 }
 269 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
 270
 271 static void cpu_device_release(struct device *dev)
 272 {
 273         /*
 274          * This is an empty function to prevent the driver core from spitting a
 275          * warning at us.  Yes, I know this is directly opposite of what the
 276          * documentation for the driver core and kobjects say, and the author
 277          * of this code has already been publically ridiculed for doing
 278          * something as foolish as this.  However, at this point in time, it is
 279          * the only way to handle the issue of statically allocated cpu
 280          * devices.  The different architectures will have their cpu device
 281          * code reworked to properly handle this in the near future, so this
 282          * function will then be changed to correctly free up the memory held
 283          * by the cpu device.
 284          *
 285          * Never copy this way of doing things, or you too will be made fun of
 286          * on the linux-kernel list, you have been warned.
 287          */
 288 }
 289
 290 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 291 static ssize_t print_cpu_modalias(struct device *dev,
 292                                   struct device_attribute *attr,
 293                                   char *buf)
 294 {
 295         ssize_t n;
 296         u32 i;
 297
 298         n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
 299                     CPU_FEATURE_TYPEVAL);
 300
 301         for (i = 0; i < MAX_CPU_FEATURES; i++)
 302                 if (cpu_have_feature(i)) {
 303                         if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
 304                                 WARN(1, "CPU features overflow page\n");
 305                                 break;
 306                         }
 307                         n += sprintf(&buf[n], ",%04X", i);
 308                 }
 309         buf[n++] = '\n';
 310         return n;
 311 }
 312
 313 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
 314 {
 315         char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 316         if (buf) {
 317                 print_cpu_modalias(NULL, NULL, buf);
 318                 add_uevent_var(env, "MODALIAS=%s", buf);
 319                 kfree(buf);
 320         }
 321         return 0;
 322 }
 323 #endif
 324
 325 /*
 326  * register_cpu - Setup a sysfs device for a CPU.
 327  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 328  *        sysfs for this CPU.
 329  * @num - CPU number to use when creating the device.
 330  *
 331  * Initialize and register the CPU device.
 332  */
 333 int register_cpu(struct cpu *cpu, int num)
 334 {
 335         int error;
 336
 337         cpu->node_id = cpu_to_node(num);
 338         memset(&cpu->dev, 0x00, sizeof(struct device));
 339         cpu->dev.id = num;
 340         cpu->dev.bus = &cpu_subsys;
 341         cpu->dev.release = cpu_device_release;
 342         cpu->dev.offline_disabled = !cpu->hotpluggable;
 343         cpu->dev.offline = !cpu_online(num);
 344         cpu->dev.of_node = of_get_cpu_node(num, NULL);
 345 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 346         cpu->dev.bus->uevent = cpu_uevent;
 347 #endif
 348         cpu->dev.groups = common_cpu_attr_groups;
 349         if (cpu->hotpluggable)
 350                 cpu->dev.groups = hotplugable_cpu_attr_groups;
 351         error = device_register(&cpu->dev);
 352         if (!error)
 353                 per_cpu(cpu_sys_devices, num) = &cpu->dev;
 354         if (!error)
 355                 register_cpu_under_node(num, cpu_to_node(num));
 356
 357         return error;
 358 }
 359
 360 struct device *get_cpu_device(unsigned cpu)
 361 {
 362         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 363                 return per_cpu(cpu_sys_devices, cpu);
 364         else
 365                 return NULL;
 366 }
 367 EXPORT_SYMBOL_GPL(get_cpu_device);
 368
 369 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 370 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
 371 #endif
 372
 373 static struct attribute *cpu_root_attrs[] = {
 374 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 375         &dev_attr_probe.attr,
 376         &dev_attr_release.attr,
 377 #endif
 378         &cpu_attrs[0].attr.attr,
 379         &cpu_attrs[1].attr.attr,
 380         &cpu_attrs[2].attr.attr,
 381         &dev_attr_kernel_max.attr,
 382         &dev_attr_offline.attr,
 383 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 384         &dev_attr_modalias.attr,
 385 #endif
 386         NULL
 387 };
 388
 389 static struct attribute_group cpu_root_attr_group = {
 390         .attrs = cpu_root_attrs,
 391 };
 392
 393 static const struct attribute_group *cpu_root_attr_groups[] = {
 394         &cpu_root_attr_group,
 395         NULL,
 396 };
 397
 398 bool cpu_is_hotpluggable(unsigned cpu)
 399 {
 400         struct device *dev = get_cpu_device(cpu);
 401         return dev && container_of(dev, struct cpu, dev)->hotpluggable;
 402 }
 403 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
 404
 405 #ifdef CONFIG_GENERIC_CPU_DEVICES
 406 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 407 #endif
 408
 409 static void __init cpu_dev_register_generic(void)
 410 {
 411 #ifdef CONFIG_GENERIC_CPU_DEVICES
 412         int i;
 413
 414         for_each_possible_cpu(i) {
 415                 if (register_cpu(&per_cpu(cpu_devices, i), i))
 416                         panic("Failed to register CPU device");
 417         }
 418 #endif
 419 }
 420
 421 void __init cpu_dev_init(void)
 422 {
 423         if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
 424                 panic("Failed to register CPU subsystem");
 425
 426         cpu_dev_register_generic();
 427 }