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