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
 211         return cpumap_print_to_pagebuf(true, buf, *ca->map);
 212 }
 213
 214 #define _CPU_ATTR(name, map) \
 215         { __ATTR(name, 0444, show_cpus_attr, NULL), map }
 216
 217 /* Keep in sync with cpu_subsys_attrs */
 218 static struct cpu_attr cpu_attrs[] = {
 219         _CPU_ATTR(online, &cpu_online_mask),
 220         _CPU_ATTR(possible, &cpu_possible_mask),
 221         _CPU_ATTR(present, &cpu_present_mask),
 222 };
 223
 224 /*
 225  * Print values for NR_CPUS and offlined cpus
 226  */
 227 static ssize_t print_cpus_kernel_max(struct device *dev,
 228                                      struct device_attribute *attr, char *buf)
 229 {
 230         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
 231         return n;
 232 }
 233 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
 234
 235 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
 236 unsigned int total_cpus;
 237
 238 static ssize_t print_cpus_offline(struct device *dev,
 239                                   struct device_attribute *attr, char *buf)
 240 {
 241         int n = 0, len = PAGE_SIZE-2;
 242         cpumask_var_t offline;
 243
 244         /* display offline cpus < nr_cpu_ids */
 245         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
 246                 return -ENOMEM;
 247         cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
 248         n = cpulist_scnprintf(buf, len, offline);
 249         free_cpumask_var(offline);
 250
 251         /* display offline cpus >= nr_cpu_ids */
 252         if (total_cpus && nr_cpu_ids < total_cpus) {
 253                 if (n && n < len)
 254                         buf[n++] = ',';
 255
 256                 if (nr_cpu_ids == total_cpus-1)
 257                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
 258                 else
 259                         n += snprintf(&buf[n], len - n, "%d-%d",
 260                                                       nr_cpu_ids, total_cpus-1);
 261         }
 262
 263         n += snprintf(&buf[n], len - n, "\n");
 264         return n;
 265 }
 266 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
 267
 268 static void cpu_device_release(struct device *dev)
 269 {
 270         /*
 271          * This is an empty function to prevent the driver core from spitting a
 272          * warning at us.  Yes, I know this is directly opposite of what the
 273          * documentation for the driver core and kobjects say, and the author
 274          * of this code has already been publically ridiculed for doing
 275          * something as foolish as this.  However, at this point in time, it is
 276          * the only way to handle the issue of statically allocated cpu
 277          * devices.  The different architectures will have their cpu device
 278          * code reworked to properly handle this in the near future, so this
 279          * function will then be changed to correctly free up the memory held
 280          * by the cpu device.
 281          *
 282          * Never copy this way of doing things, or you too will be made fun of
 283          * on the linux-kernel list, you have been warned.
 284          */
 285 }
 286
 287 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 288 static ssize_t print_cpu_modalias(struct device *dev,
 289                                   struct device_attribute *attr,
 290                                   char *buf)
 291 {
 292         ssize_t n;
 293         u32 i;
 294
 295         n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
 296                     CPU_FEATURE_TYPEVAL);
 297
 298         for (i = 0; i < MAX_CPU_FEATURES; i++)
 299                 if (cpu_have_feature(i)) {
 300                         if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
 301                                 WARN(1, "CPU features overflow page\n");
 302                                 break;
 303                         }
 304                         n += sprintf(&buf[n], ",%04X", i);
 305                 }
 306         buf[n++] = '\n';
 307         return n;
 308 }
 309
 310 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
 311 {
 312         char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 313         if (buf) {
 314                 print_cpu_modalias(NULL, NULL, buf);
 315                 add_uevent_var(env, "MODALIAS=%s", buf);
 316                 kfree(buf);
 317         }
 318         return 0;
 319 }
 320 #endif
 321
 322 /*
 323  * register_cpu - Setup a sysfs device for a CPU.
 324  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 325  *        sysfs for this CPU.
 326  * @num - CPU number to use when creating the device.
 327  *
 328  * Initialize and register the CPU device.
 329  */
 330 int register_cpu(struct cpu *cpu, int num)
 331 {
 332         int error;
 333
 334         cpu->node_id = cpu_to_node(num);
 335         memset(&cpu->dev, 0x00, sizeof(struct device));
 336         cpu->dev.id = num;
 337         cpu->dev.bus = &cpu_subsys;
 338         cpu->dev.release = cpu_device_release;
 339         cpu->dev.offline_disabled = !cpu->hotpluggable;
 340         cpu->dev.offline = !cpu_online(num);
 341         cpu->dev.of_node = of_get_cpu_node(num, NULL);
 342 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 343         cpu->dev.bus->uevent = cpu_uevent;
 344 #endif
 345         cpu->dev.groups = common_cpu_attr_groups;
 346         if (cpu->hotpluggable)
 347                 cpu->dev.groups = hotplugable_cpu_attr_groups;
 348         error = device_register(&cpu->dev);
 349         if (!error)
 350                 per_cpu(cpu_sys_devices, num) = &cpu->dev;
 351         if (!error)
 352                 register_cpu_under_node(num, cpu_to_node(num));
 353
 354         return error;
 355 }
 356
 357 struct device *get_cpu_device(unsigned cpu)
 358 {
 359         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 360                 return per_cpu(cpu_sys_devices, cpu);
 361         else
 362                 return NULL;
 363 }
 364 EXPORT_SYMBOL_GPL(get_cpu_device);
 365
 366 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 367 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
 368 #endif
 369
 370 static struct attribute *cpu_root_attrs[] = {
 371 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 372         &dev_attr_probe.attr,
 373         &dev_attr_release.attr,
 374 #endif
 375         &cpu_attrs[0].attr.attr,
 376         &cpu_attrs[1].attr.attr,
 377         &cpu_attrs[2].attr.attr,
 378         &dev_attr_kernel_max.attr,
 379         &dev_attr_offline.attr,
 380 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
 381         &dev_attr_modalias.attr,
 382 #endif
 383         NULL
 384 };
 385
 386 static struct attribute_group cpu_root_attr_group = {
 387         .attrs = cpu_root_attrs,
 388 };
 389
 390 static const struct attribute_group *cpu_root_attr_groups[] = {
 391         &cpu_root_attr_group,
 392         NULL,
 393 };
 394
 395 bool cpu_is_hotpluggable(unsigned cpu)
 396 {
 397         struct device *dev = get_cpu_device(cpu);
 398         return dev && container_of(dev, struct cpu, dev)->hotpluggable;
 399 }
 400 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
 401
 402 #ifdef CONFIG_GENERIC_CPU_DEVICES
 403 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 404 #endif
 405
 406 static void __init cpu_dev_register_generic(void)
 407 {
 408 #ifdef CONFIG_GENERIC_CPU_DEVICES
 409         int i;
 410
 411         for_each_possible_cpu(i) {
 412                 if (register_cpu(&per_cpu(cpu_devices, i), i))
 413                         panic("Failed to register CPU device");
 414         }
 415 #endif
 416 }
 417
 418 void __init cpu_dev_init(void)
 419 {
 420         if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
 421                 panic("Failed to register CPU subsystem");
 422
 423         cpu_dev_register_generic();
 424 }