kernel/include/linux/cpu.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * 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/cpuhotplug.h>
#include <linux/cpuhplock.h>
#include <linux/cpu_smt.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_hotplug_init(void);
extern void cpu_init(void);
extern void trap_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 ssize_t cpu_show_l1tf(struct device *dev,
			     struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_mds(struct device *dev,
			    struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_tsx_async_abort(struct device *dev,
					struct device_attribute *attr,
					char *buf);
extern ssize_t cpu_show_itlb_multihit(struct device *dev,
				      struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_mmio_stale_data(struct device *dev,
					struct device_attribute *attr,
					char *buf);
extern ssize_t cpu_show_retbleed(struct device *dev,
				 struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_spec_rstack_overflow(struct device *dev,
					     struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_gds(struct device *dev,
			    struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_reg_file_data_sampling(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, ...);
extern bool arch_cpu_is_hotpluggable(int cpu);
extern int arch_register_cpu(int cpu);
extern void arch_unregister_cpu(int cpu);
#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

#ifdef CONFIG_GENERIC_CPU_DEVICES
DECLARE_PER_CPU(struct cpu, cpu_devices);
#endif

/*
 * These states are not related to the core CPU hotplug mechanism. They are
 * used by various (sub)architectures to track internal state
 */
#define CPU_ONLINE		0x0002 /* CPU is up */
#define CPU_UP_PREPARE		0x0003 /* CPU coming up */
#define CPU_DEAD		0x0007 /* CPU dead */
#define CPU_DEAD_FROZEN		0x0008 /* CPU timed out on unplug */
#define CPU_POST_DEAD		0x0009 /* CPU successfully unplugged */
#define CPU_BROKEN		0x000B /* CPU did not die properly */

#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
int add_cpu(unsigned int cpu);
int cpu_device_up(struct device *dev);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);
int bringup_hibernate_cpu(unsigned int sleep_cpu);
void bringup_nonboot_cpus(unsigned int max_cpus);

#else	/* CONFIG_SMP */
#define cpuhp_tasks_frozen	0

static inline void cpu_maps_update_begin(void)
{
}

static inline void cpu_maps_update_done(void)
{
}

static inline int add_cpu(unsigned int cpu) { return 0;}

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

#ifdef CONFIG_PM_SLEEP_SMP
extern int freeze_secondary_cpus(int primary);
extern void thaw_secondary_cpus(void);

static inline int suspend_disable_secondary_cpus(void)
{
	int cpu = 0;

	if (IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU))
		cpu = -1;

	return freeze_secondary_cpus(cpu);
}
static inline void suspend_enable_secondary_cpus(void)
{
	return thaw_secondary_cpus();
}

#else /* !CONFIG_PM_SLEEP_SMP */
static inline void thaw_secondary_cpus(void) {}
static inline int suspend_disable_secondary_cpus(void) { return 0; }
static inline void suspend_enable_secondary_cpus(void) { }
#endif /* !CONFIG_PM_SLEEP_SMP */

void __noreturn cpu_startup_entry(enum cpuhp_state state);

void cpu_idle_poll_ctrl(bool enable);

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_tick_broadcast_enter(void);
void arch_tick_broadcast_exit(void);
void __noreturn arch_cpu_idle_dead(void);

#ifdef CONFIG_ARCH_HAS_CPU_FINALIZE_INIT
void arch_cpu_finalize_init(void);
#else
static inline void arch_cpu_finalize_init(void) { }
#endif

void play_idle_precise(u64 duration_ns, u64 latency_ns);

static inline void play_idle(unsigned long duration_us)
{
	play_idle_precise(duration_us * NSEC_PER_USEC, U64_MAX);
}

#ifdef CONFIG_HOTPLUG_CPU
void cpuhp_report_idle_dead(void);
#else
static inline void cpuhp_report_idle_dead(void) { }
#endif /* #ifdef CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_CPU_MITIGATIONS
extern bool cpu_mitigations_off(void);
extern bool cpu_mitigations_auto_nosmt(void);
#else
static inline bool cpu_mitigations_off(void)
{
	return true;
}
static inline bool cpu_mitigations_auto_nosmt(void)
{
	return false;
}
#endif

#endif /* _LINUX_CPU_H_ */