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