// SPDX-License-Identifier: GPL-2.0

  /*

   * CPU subsystem support

   */

  #include <linux/kernel.h>

  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/sched.h>

  #include <linux/cpu.h>
  #include <linux/topology.h>
  #include <linux/device.h>

  #include <linux/node.h>

  #include <linux/gfp.h>

  #include <linux/slab.h>

  #include <linux/percpu.h>

  #include <linux/acpi.h>

  #include <linux/of.h>

  #include <linux/cpufeature.h>

  #include <linux/tick.h>

  #include <linux/pm_qos.h>

  #include <linux/sched/isolation.h>

  #include "base.h"

  static DEFINE_PER_CPU(struct device *, cpu_sys_devices);

  static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
  {
  	/* ACPI style match is the only one that may succeed. */
  	if (acpi_driver_match_device(dev, drv))
  		return 1;
  
  	return 0;
  }

  #ifdef CONFIG_HOTPLUG_CPU

  static void change_cpu_under_node(struct cpu *cpu,
  			unsigned int from_nid, unsigned int to_nid)
  {
  	int cpuid = cpu->dev.id;
  	unregister_cpu_under_node(cpuid, from_nid);
  	register_cpu_under_node(cpuid, to_nid);
  	cpu->node_id = to_nid;
  }

  static int cpu_subsys_online(struct device *dev)

  {

  	struct cpu *cpu = container_of(dev, struct cpu, dev);

  	int cpuid = dev->id;
  	int from_nid, to_nid;

  	int ret;

  	from_nid = cpu_to_node(cpuid);

  	if (from_nid == NUMA_NO_NODE)

  		return -ENODEV;

  	ret = cpu_device_up(dev);

  	/*
  	 * When hot adding memory to memoryless node and enabling a cpu
  	 * on the node, node number of the cpu may internally change.
  	 */
  	to_nid = cpu_to_node(cpuid);
  	if (from_nid != to_nid)
  		change_cpu_under_node(cpu, from_nid, to_nid);

  	return ret;

  }

  static int cpu_subsys_offline(struct device *dev)

  {

  	return cpu_device_down(dev);

  }

  void unregister_cpu(struct cpu *cpu)

  {

  	int logical_cpu = cpu->dev.id;

  	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));

  	device_unregister(&cpu->dev);

  	per_cpu(cpu_sys_devices, logical_cpu) = NULL;

  	return;
  }

  
  #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

  static ssize_t cpu_probe_store(struct device *dev,
  			       struct device_attribute *attr,

  			       const char *buf,

  			       size_t count)
  {

  	ssize_t cnt;
  	int ret;
  
  	ret = lock_device_hotplug_sysfs();
  	if (ret)
  		return ret;
  
  	cnt = arch_cpu_probe(buf, count);
  
  	unlock_device_hotplug();
  	return cnt;

  }

  static ssize_t cpu_release_store(struct device *dev,
  				 struct device_attribute *attr,

  				 const char *buf,

  				 size_t count)
  {

  	ssize_t cnt;
  	int ret;
  
  	ret = lock_device_hotplug_sysfs();
  	if (ret)
  		return ret;
  
  	cnt = arch_cpu_release(buf, count);
  
  	unlock_device_hotplug();
  	return cnt;

  }

  static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
  static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);

  #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

  #endif /* CONFIG_HOTPLUG_CPU */

  struct bus_type cpu_subsys = {
  	.name = "cpu",
  	.dev_name = "cpu",

  	.match = cpu_subsys_match,

  #ifdef CONFIG_HOTPLUG_CPU
  	.online = cpu_subsys_online,
  	.offline = cpu_subsys_offline,
  #endif
  };
  EXPORT_SYMBOL_GPL(cpu_subsys);

  #ifdef CONFIG_KEXEC
  #include <linux/kexec.h>

  static ssize_t crash_notes_show(struct device *dev,
  				struct device_attribute *attr,

  				char *buf)

  {

  	struct cpu *cpu = container_of(dev, struct cpu, dev);

  	unsigned long long addr;
  	int cpunum;

  	cpunum = cpu->dev.id;

  
  	/*
  	 * Might be reading other cpu's data based on which cpu read thread
  	 * has been scheduled. But cpu data (memory) is allocated once during
  	 * boot up and this data does not change there after. Hence this
  	 * operation should be safe. No locking required.
  	 */

  	addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));

  
  	return sysfs_emit(buf, "%llx
  ", addr);

  }

  static DEVICE_ATTR_ADMIN_RO(crash_notes);

  static ssize_t crash_notes_size_show(struct device *dev,

  				     struct device_attribute *attr,
  				     char *buf)
  {

  	return sysfs_emit(buf, "%zu
  ", sizeof(note_buf_t));

  }

  static DEVICE_ATTR_ADMIN_RO(crash_notes_size);

  
  static struct attribute *crash_note_cpu_attrs[] = {
  	&dev_attr_crash_notes.attr,
  	&dev_attr_crash_notes_size.attr,
  	NULL
  };
  
  static struct attribute_group crash_note_cpu_attr_group = {
  	.attrs = crash_note_cpu_attrs,
  };
  #endif
  
  static const struct attribute_group *common_cpu_attr_groups[] = {
  #ifdef CONFIG_KEXEC
  	&crash_note_cpu_attr_group,

  #endif

  	NULL
  };

  static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
  #ifdef CONFIG_KEXEC
  	&crash_note_cpu_attr_group,
  #endif

  	NULL
  };

  /*

   * Print cpu online, possible, present, and system maps
   */

  
  struct cpu_attr {

  	struct device_attribute attr;

  	const struct cpumask *const map;

  };

  static ssize_t show_cpus_attr(struct device *dev,
  			      struct device_attribute *attr,

  			      char *buf)

  {

  	struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);

  	return cpumap_print_to_pagebuf(true, buf, ca->map);

  }

  #define _CPU_ATTR(name, map) \
  	{ __ATTR(name, 0444, show_cpus_attr, NULL), map }

  /* Keep in sync with cpu_subsys_attrs */

  static struct cpu_attr cpu_attrs[] = {

  	_CPU_ATTR(online, &__cpu_online_mask),
  	_CPU_ATTR(possible, &__cpu_possible_mask),
  	_CPU_ATTR(present, &__cpu_present_mask),

  };

  /*
   * Print values for NR_CPUS and offlined cpus
   */

  static ssize_t print_cpus_kernel_max(struct device *dev,
  				     struct device_attribute *attr, char *buf)

  {

  	return sysfs_emit(buf, "%d
  ", NR_CPUS - 1);

  }

  static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);

  
  /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
  unsigned int total_cpus;

  static ssize_t print_cpus_offline(struct device *dev,
  				  struct device_attribute *attr, char *buf)

  {

  	int len = 0;

  	cpumask_var_t offline;
  
  	/* display offline cpus < nr_cpu_ids */
  	if (!alloc_cpumask_var(&offline, GFP_KERNEL))
  		return -ENOMEM;

  	cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);

  	len += sysfs_emit_at(buf, len, "%*pbl", cpumask_pr_args(offline));

  	free_cpumask_var(offline);
  
  	/* display offline cpus >= nr_cpu_ids */
  	if (total_cpus && nr_cpu_ids < total_cpus) {

  		len += sysfs_emit_at(buf, len, ",");

  
  		if (nr_cpu_ids == total_cpus-1)

  			len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids);

  		else

  			len += sysfs_emit_at(buf, len, "%u-%d",
  					     nr_cpu_ids, total_cpus - 1);

  	}

  	len += sysfs_emit_at(buf, len, "
  ");
  
  	return len;

  }

  static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);

  static ssize_t print_cpus_isolated(struct device *dev,
  				  struct device_attribute *attr, char *buf)
  {

  	int len;

  	cpumask_var_t isolated;

  	if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
  		return -ENOMEM;
  
  	cpumask_andnot(isolated, cpu_possible_mask,
  		       housekeeping_cpumask(HK_FLAG_DOMAIN));

  	len = sysfs_emit(buf, "%*pbl
  ", cpumask_pr_args(isolated));

  
  	free_cpumask_var(isolated);

  	return len;

  }
  static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);

  #ifdef CONFIG_NO_HZ_FULL
  static ssize_t print_cpus_nohz_full(struct device *dev,

  				    struct device_attribute *attr, char *buf)

  {

  	return sysfs_emit(buf, "%*pbl
  ", cpumask_pr_args(tick_nohz_full_mask));

  }
  static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
  #endif

  static void cpu_device_release(struct device *dev)
  {
  	/*
  	 * This is an empty function to prevent the driver core from spitting a
  	 * warning at us.  Yes, I know this is directly opposite of what the
  	 * documentation for the driver core and kobjects say, and the author
  	 * of this code has already been publically ridiculed for doing
  	 * something as foolish as this.  However, at this point in time, it is
  	 * the only way to handle the issue of statically allocated cpu
  	 * devices.  The different architectures will have their cpu device
  	 * code reworked to properly handle this in the near future, so this
  	 * function will then be changed to correctly free up the memory held
  	 * by the cpu device.
  	 *
  	 * Never copy this way of doing things, or you too will be made fun of

  	 * on the linux-kernel list, you have been warned.

  	 */
  }

  #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  static ssize_t print_cpu_modalias(struct device *dev,
  				  struct device_attribute *attr,
  				  char *buf)
  {

  	int len = 0;

  	u32 i;

  	len += sysfs_emit_at(buf, len,
  			     "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
  			     CPU_FEATURE_TYPEVAL);

  
  	for (i = 0; i < MAX_CPU_FEATURES; i++)
  		if (cpu_have_feature(i)) {

  			if (len + sizeof(",XXXX
  ") >= PAGE_SIZE) {

  				WARN(1, "CPU features overflow page
  ");
  				break;
  			}

  			len += sysfs_emit_at(buf, len, ",%04X", i);

  		}

  	len += sysfs_emit_at(buf, len, "
  ");
  	return len;

  }

  
  static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
  {
  	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
  	if (buf) {
  		print_cpu_modalias(NULL, NULL, buf);
  		add_uevent_var(env, "MODALIAS=%s", buf);
  		kfree(buf);
  	}
  	return 0;
  }
  #endif

  /*

   * register_cpu - Setup a sysfs device for a CPU.

   * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
   *	  sysfs for this CPU.

   * @num - CPU number to use when creating the device.
   *
   * Initialize and register the CPU device.
   */

  int register_cpu(struct cpu *cpu, int num)

  {
  	int error;

  	cpu->node_id = cpu_to_node(num);

  	memset(&cpu->dev, 0x00, sizeof(struct device));

  	cpu->dev.id = num;
  	cpu->dev.bus = &cpu_subsys;

  	cpu->dev.release = cpu_device_release;

  	cpu->dev.offline_disabled = !cpu->hotpluggable;

  	cpu->dev.offline = !cpu_online(num);

  	cpu->dev.of_node = of_get_cpu_node(num, NULL);

  #ifdef CONFIG_GENERIC_CPU_AUTOPROBE

  	cpu->dev.bus->uevent = cpu_uevent;

  #endif

  	cpu->dev.groups = common_cpu_attr_groups;

  	if (cpu->hotpluggable)
  		cpu->dev.groups = hotplugable_cpu_attr_groups;

  	error = device_register(&cpu->dev);

  	if (error) {
  		put_device(&cpu->dev);

  		return error;

  	}

  	per_cpu(cpu_sys_devices, num) = &cpu->dev;
  	register_cpu_under_node(num, cpu_to_node(num));

  	dev_pm_qos_expose_latency_limit(&cpu->dev,
  					PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);

  
  	return 0;

  }

  struct device *get_cpu_device(unsigned cpu)

  {

  	if (cpu < nr_cpu_ids && cpu_possible(cpu))
  		return per_cpu(cpu_sys_devices, cpu);

  	else
  		return NULL;
  }

  EXPORT_SYMBOL_GPL(get_cpu_device);

  static void device_create_release(struct device *dev)
  {
  	kfree(dev);
  }

  __printf(4, 0)

  static struct device *
  __cpu_device_create(struct device *parent, void *drvdata,
  		    const struct attribute_group **groups,
  		    const char *fmt, va_list args)
  {
  	struct device *dev = NULL;
  	int retval = -ENODEV;
  
  	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
  	if (!dev) {
  		retval = -ENOMEM;
  		goto error;
  	}
  
  	device_initialize(dev);
  	dev->parent = parent;
  	dev->groups = groups;
  	dev->release = device_create_release;

  	device_set_pm_not_required(dev);

  	dev_set_drvdata(dev, drvdata);
  
  	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
  	if (retval)
  		goto error;
  
  	retval = device_add(dev);
  	if (retval)
  		goto error;
  
  	return dev;
  
  error:
  	put_device(dev);
  	return ERR_PTR(retval);
  }
  
  struct device *cpu_device_create(struct device *parent, void *drvdata,
  				 const struct attribute_group **groups,
  				 const char *fmt, ...)
  {
  	va_list vargs;
  	struct device *dev;
  
  	va_start(vargs, fmt);
  	dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
  	va_end(vargs);
  	return dev;
  }
  EXPORT_SYMBOL_GPL(cpu_device_create);

  #ifdef CONFIG_GENERIC_CPU_AUTOPROBE

  static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);

  #endif

  static struct attribute *cpu_root_attrs[] = {
  #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  	&dev_attr_probe.attr,
  	&dev_attr_release.attr,
  #endif
  	&cpu_attrs[0].attr.attr,
  	&cpu_attrs[1].attr.attr,
  	&cpu_attrs[2].attr.attr,
  	&dev_attr_kernel_max.attr,
  	&dev_attr_offline.attr,

  	&dev_attr_isolated.attr,

  #ifdef CONFIG_NO_HZ_FULL
  	&dev_attr_nohz_full.attr,
  #endif

  #ifdef CONFIG_GENERIC_CPU_AUTOPROBE

  	&dev_attr_modalias.attr,
  #endif

  	NULL
  };
  
  static struct attribute_group cpu_root_attr_group = {
  	.attrs = cpu_root_attrs,
  };
  
  static const struct attribute_group *cpu_root_attr_groups[] = {
  	&cpu_root_attr_group,
  	NULL,
  };

  bool cpu_is_hotpluggable(unsigned cpu)
  {

  	struct device *dev = get_cpu_device(cpu);
  	return dev && container_of(dev, struct cpu, dev)->hotpluggable;

  }
  EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);

  #ifdef CONFIG_GENERIC_CPU_DEVICES
  static DEFINE_PER_CPU(struct cpu, cpu_devices);
  #endif
  
  static void __init cpu_dev_register_generic(void)
  {
  #ifdef CONFIG_GENERIC_CPU_DEVICES
  	int i;
  
  	for_each_possible_cpu(i) {
  		if (register_cpu(&per_cpu(cpu_devices, i), i))
  			panic("Failed to register CPU device");
  	}
  #endif
  }

  #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
  
  ssize_t __weak cpu_show_meltdown(struct device *dev,
  				 struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }
  
  ssize_t __weak cpu_show_spectre_v1(struct device *dev,
  				   struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }
  
  ssize_t __weak cpu_show_spectre_v2(struct device *dev,
  				   struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  ssize_t __weak cpu_show_spec_store_bypass(struct device *dev,
  					  struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  ssize_t __weak cpu_show_l1tf(struct device *dev,
  			     struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  ssize_t __weak cpu_show_mds(struct device *dev,
  			    struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  ssize_t __weak cpu_show_tsx_async_abort(struct device *dev,
  					struct device_attribute *attr,
  					char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  ssize_t __weak cpu_show_itlb_multihit(struct device *dev,

  				      struct device_attribute *attr, char *buf)

  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  ssize_t __weak cpu_show_srbds(struct device *dev,
  			      struct device_attribute *attr, char *buf)
  {

  	return sysfs_emit(buf, "Not affected
  ");

  }

  static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
  static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
  static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);

  static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);

  static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);

  static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);

  static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);

  static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);

  static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);

  
  static struct attribute *cpu_root_vulnerabilities_attrs[] = {
  	&dev_attr_meltdown.attr,
  	&dev_attr_spectre_v1.attr,
  	&dev_attr_spectre_v2.attr,

  	&dev_attr_spec_store_bypass.attr,

  	&dev_attr_l1tf.attr,

  	&dev_attr_mds.attr,

  	&dev_attr_tsx_async_abort.attr,

  	&dev_attr_itlb_multihit.attr,

  	&dev_attr_srbds.attr,

  	NULL
  };
  
  static const struct attribute_group cpu_root_vulnerabilities_group = {
  	.name  = "vulnerabilities",
  	.attrs = cpu_root_vulnerabilities_attrs,
  };
  
  static void __init cpu_register_vulnerabilities(void)
  {
  	if (sysfs_create_group(&cpu_subsys.dev_root->kobj,
  			       &cpu_root_vulnerabilities_group))
  		pr_err("Unable to register CPU vulnerabilities
  ");
  }
  
  #else
  static inline void cpu_register_vulnerabilities(void) { }
  #endif

  void __init cpu_dev_init(void)

  {

  	if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
  		panic("Failed to register CPU subsystem");

  	cpu_dev_register_generic();

  	cpu_register_vulnerabilities();

  }