linux/include/linux/cpu.h

/*
 * include/linux/cpu.h - generic cpu definition
 *
 * This is mainly for topological representation. We define the 
 * basic 'struct cpu' here, which can be embedded in per-arch 
 * definitions of processors.
 *
 * Basic handling of the devices is done in drivers/base/cpu.c
 *
 * CPUs are exported via sysfs in the devices/system/cpu
 * directory. 
 */
#ifndef _LINUX_CPU_H_
#define _LINUX_CPU_H_

#include <linux/node.h>
#include <linux/compiler.h>
#include <linux/cpumask.h>
#include <linux/cpuhotplug.h>

struct device;
struct device_node;
struct attribute_group;

struct cpu {
	int node_id;		/* The node which contains the CPU */
	int hotpluggable;	/* creates sysfs control file if hotpluggable */
	struct device dev;
};

extern void boot_cpu_init(void);
extern void boot_cpu_state_init(void);

extern int register_cpu(struct cpu *cpu, int num);
extern struct device *get_cpu_device(unsigned cpu);
extern bool cpu_is_hotpluggable(unsigned cpu);
extern bool arch_match_cpu_phys_id(int cpu, u64 phys_id);
extern bool arch_find_n_match_cpu_physical_id(struct device_node *cpun,
					      int cpu, unsigned int *thread);

extern int cpu_add_dev_attr(struct device_attribute *attr);
extern void cpu_remove_dev_attr(struct device_attribute *attr);

extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);

extern ssize_t cpu_show_meltdown(struct device *dev,
				 struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spectre_v1(struct device *dev,
				   struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spectre_v2(struct device *dev,
				   struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
					  struct device_attribute *attr, char *buf);

extern __printf(4, 5)
struct device *cpu_device_create(struct device *parent, void *drvdata,
				 const struct attribute_group **groups,
				 const char *fmt, ...);
#ifdef CONFIG_HOTPLUG_CPU
extern void unregister_cpu(struct cpu *cpu);
extern ssize_t arch_cpu_probe(const char *, size_t);
extern ssize_t arch_cpu_release(const char *, size_t);
#endif
struct notifier_block;

#define CPU_ONLINE		0x0002 /* CPU (unsigned)v is up */
#define CPU_UP_PREPARE		0x0003 /* CPU (unsigned)v coming up */
#define CPU_UP_CANCELED		0x0004 /* CPU (unsigned)v NOT coming up */
#define CPU_DOWN_PREPARE	0x0005 /* CPU (unsigned)v going down */
#define CPU_DOWN_FAILED		0x0006 /* CPU (unsigned)v NOT going down */
#define CPU_DEAD		0x0007 /* CPU (unsigned)v dead */
#define CPU_POST_DEAD		0x0009 /* CPU (unsigned)v dead, cpu_hotplug
					* lock is dropped */
#define CPU_BROKEN		0x000B /* CPU (unsigned)v did not die properly,
					* perhaps due to preemption. */

/* Used for CPU hotplug events occurring while tasks are frozen due to a suspend
 * operation in progress
 */
#define CPU_TASKS_FROZEN	0x0010

#define CPU_ONLINE_FROZEN	(CPU_ONLINE | CPU_TASKS_FROZEN)
#define CPU_UP_PREPARE_FROZEN	(CPU_UP_PREPARE | CPU_TASKS_FROZEN)
#define CPU_UP_CANCELED_FROZEN	(CPU_UP_CANCELED | CPU_TASKS_FROZEN)
#define CPU_DOWN_PREPARE_FROZEN	(CPU_DOWN_PREPARE | CPU_TASKS_FROZEN)
#define CPU_DOWN_FAILED_FROZEN	(CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
#define CPU_DEAD_FROZEN		(CPU_DEAD | CPU_TASKS_FROZEN)

#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
/* Need to know about CPUs going up/down? */
#if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE)
#define cpu_notifier(fn, pri) {					\
	static struct notifier_block fn##_nb =			\
		{ .notifier_call = fn, .priority = pri };	\
	register_cpu_notifier(&fn##_nb);			\
}

#define __cpu_notifier(fn, pri) {				\
	static struct notifier_block fn##_nb =			\
		{ .notifier_call = fn, .priority = pri };	\
	__register_cpu_notifier(&fn##_nb);			\
}

extern int register_cpu_notifier(struct notifier_block *nb);
extern int __register_cpu_notifier(struct notifier_block *nb);
extern void unregister_cpu_notifier(struct notifier_block *nb);
extern void __unregister_cpu_notifier(struct notifier_block *nb);

#else /* #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */
#define cpu_notifier(fn, pri)	do { (void)(fn); } while (0)
#define __cpu_notifier(fn, pri)	do { (void)(fn); } while (0)

static inline int register_cpu_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline int __register_cpu_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline void unregister_cpu_notifier(struct notifier_block *nb)
{
}

static inline void __unregister_cpu_notifier(struct notifier_block *nb)
{
}
#endif

int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);

#define cpu_notifier_register_begin	cpu_maps_update_begin
#define cpu_notifier_register_done	cpu_maps_update_done

#else	/* CONFIG_SMP */
#define cpuhp_tasks_frozen	0

#define cpu_notifier(fn, pri)	do { (void)(fn); } while (0)
#define __cpu_notifier(fn, pri)	do { (void)(fn); } while (0)

static inline int register_cpu_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline int __register_cpu_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline void unregister_cpu_notifier(struct notifier_block *nb)
{
}

static inline void __unregister_cpu_notifier(struct notifier_block *nb)
{
}

static inline void cpu_maps_update_begin(void)
{
}

static inline void cpu_maps_update_done(void)
{
}

static inline void cpu_notifier_register_begin(void)
{
}

static inline void cpu_notifier_register_done(void)
{
}

#endif /* CONFIG_SMP */
extern struct bus_type cpu_subsys;

#ifdef CONFIG_HOTPLUG_CPU
/* Stop CPUs going up and down. */

extern void cpu_hotplug_begin(void);
extern void cpu_hotplug_done(void);
extern void get_online_cpus(void);
extern void put_online_cpus(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
#define hotcpu_notifier(fn, pri)	cpu_notifier(fn, pri)
#define __hotcpu_notifier(fn, pri)	__cpu_notifier(fn, pri)
#define register_hotcpu_notifier(nb)	register_cpu_notifier(nb)
#define __register_hotcpu_notifier(nb)	__register_cpu_notifier(nb)
#define unregister_hotcpu_notifier(nb)	unregister_cpu_notifier(nb)
#define __unregister_hotcpu_notifier(nb)	__unregister_cpu_notifier(nb)
void clear_tasks_mm_cpumask(int cpu);
int cpu_down(unsigned int cpu);

#else		/* CONFIG_HOTPLUG_CPU */

static inline void cpu_hotplug_begin(void) {}
static inline void cpu_hotplug_done(void) {}
#define get_online_cpus()	do { } while (0)
#define put_online_cpus()	do { } while (0)
#define cpu_hotplug_disable()	do { } while (0)
#define cpu_hotplug_enable()	do { } while (0)
#define hotcpu_notifier(fn, pri)	do { (void)(fn); } while (0)
#define __hotcpu_notifier(fn, pri)	do { (void)(fn); } while (0)
/* These aren't inline functions due to a GCC bug. */
#define register_hotcpu_notifier(nb)	({ (void)(nb); 0; })
#define __register_hotcpu_notifier(nb)	({ (void)(nb); 0; })
#define unregister_hotcpu_notifier(nb)	({ (void)(nb); })
#define __unregister_hotcpu_notifier(nb)	({ (void)(nb); })
#endif		/* CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_PM_SLEEP_SMP
extern int freeze_secondary_cpus(int primary);
static inline int disable_nonboot_cpus(void)
{
	return freeze_secondary_cpus(0);
}
extern void enable_nonboot_cpus(void);
#else /* !CONFIG_PM_SLEEP_SMP */
static inline int disable_nonboot_cpus(void) { return 0; }
static inline void enable_nonboot_cpus(void) {}
#endif /* !CONFIG_PM_SLEEP_SMP */

void cpu_startup_entry(enum cpuhp_state state);

void cpu_idle_poll_ctrl(bool enable);

/* Attach to any functions which should be considered cpuidle. */
#define __cpuidle	__attribute__((__section__(".cpuidle.text")))

bool cpu_in_idle(unsigned long pc);

void arch_cpu_idle(void);
void arch_cpu_idle_prepare(void);
void arch_cpu_idle_enter(void);
void arch_cpu_idle_exit(void);
void arch_cpu_idle_dead(void);

int cpu_report_state(int cpu);
int cpu_check_up_prepare(int cpu);
void cpu_set_state_online(int cpu);
#ifdef CONFIG_HOTPLUG_CPU
bool cpu_wait_death(unsigned int cpu, int seconds);
bool cpu_report_death(void);
void cpuhp_report_idle_dead(void);
#else
static inline void cpuhp_report_idle_dead(void) { }
#endif /* #ifdef CONFIG_HOTPLUG_CPU */

#define IDLE_START 1
#define IDLE_END 2

void idle_notifier_register(struct notifier_block *n);
void idle_notifier_unregister(struct notifier_block *n);
void idle_notifier_call_chain(unsigned long val);

#endif /* _LINUX_CPU_H_ */