alistair23-linux/include/linux/smp.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_SMP_H
#define __LINUX_SMP_H

/*
 *	Generic SMP support
 *		Alan Cox. <alan@redhat.com>
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/llist.h>

typedef void (*smp_call_func_t)(void *info);
typedef bool (*smp_cond_func_t)(int cpu, void *info);

enum {
	CSD_FLAG_LOCK		= 0x01,

	/* IRQ_WORK_flags */

	CSD_TYPE_ASYNC		= 0x00,
	CSD_TYPE_SYNC		= 0x10,
	CSD_TYPE_IRQ_WORK	= 0x20,
	CSD_TYPE_TTWU		= 0x30,
	CSD_FLAG_TYPE_MASK	= 0xF0,
};

/*
 * structure shares (partial) layout with struct irq_work
 */
struct __call_single_data {
	struct llist_node llist;
	unsigned int flags;
	smp_call_func_t func;
	void *info;
};

/* Use __aligned() to avoid to use 2 cache lines for 1 csd */
typedef struct __call_single_data call_single_data_t
	__aligned(sizeof(struct __call_single_data));

/*
 * Enqueue a llist_node on the call_single_queue; be very careful, read
 * flush_smp_call_function_queue() in detail.
 */
extern void __smp_call_single_queue(int cpu, struct llist_node *node);

/* total number of cpus in this system (may exceed NR_CPUS) */
extern unsigned int total_cpus;

int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
			     int wait);

/*
 * Call a function on all processors
 */
void on_each_cpu(smp_call_func_t func, void *info, int wait);

/*
 * Call a function on processors specified by mask, which might include
 * the local one.
 */
void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
		void *info, bool wait);

/*
 * Call a function on each processor for which the supplied function
 * cond_func returns a positive value. This may include the local
 * processor.
 */
void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
		      void *info, bool wait);

void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
			   void *info, bool wait, const struct cpumask *mask);

int smp_call_function_single_async(int cpu, call_single_data_t *csd);

#ifdef CONFIG_SMP

#include <linux/preempt.h>
#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/thread_info.h>
#include <asm/smp.h>

/*
 * main cross-CPU interfaces, handles INIT, TLB flush, STOP, etc.
 * (defined in asm header):
 */

/*
 * stops all CPUs but the current one:
 */
extern void smp_send_stop(void);

/*
 * sends a 'reschedule' event to another CPU:
 */
extern void smp_send_reschedule(int cpu);


/*
 * Prepare machine for booting other CPUs.
 */
extern void smp_prepare_cpus(unsigned int max_cpus);

/*
 * Bring a CPU up
 */
extern int __cpu_up(unsigned int cpunum, struct task_struct *tidle);

/*
 * Final polishing of CPUs
 */
extern void smp_cpus_done(unsigned int max_cpus);

/*
 * Call a function on all other processors
 */
void smp_call_function(smp_call_func_t func, void *info, int wait);
void smp_call_function_many(const struct cpumask *mask,
			    smp_call_func_t func, void *info, bool wait);

int smp_call_function_any(const struct cpumask *mask,
			  smp_call_func_t func, void *info, int wait);

void kick_all_cpus_sync(void);
void wake_up_all_idle_cpus(void);

/*
 * Generic and arch helpers
 */
void __init call_function_init(void);
void generic_smp_call_function_single_interrupt(void);
#define generic_smp_call_function_interrupt \
	generic_smp_call_function_single_interrupt

/*
 * Mark the boot cpu "online" so that it can call console drivers in
 * printk() and can access its per-cpu storage.
 */
void smp_prepare_boot_cpu(void);

extern unsigned int setup_max_cpus;
extern void __init setup_nr_cpu_ids(void);
extern void __init smp_init(void);

extern int __boot_cpu_id;

static inline int get_boot_cpu_id(void)
{
	return __boot_cpu_id;
}

#else /* !SMP */

static inline void smp_send_stop(void) { }

/*
 *	These macros fold the SMP functionality into a single CPU system
 */
#define raw_smp_processor_id()			0
static inline void up_smp_call_function(smp_call_func_t func, void *info)
{
}
#define smp_call_function(func, info, wait) \
			(up_smp_call_function(func, info))

static inline void smp_send_reschedule(int cpu) { }
#define smp_prepare_boot_cpu()			do {} while (0)
#define smp_call_function_many(mask, func, info, wait) \
			(up_smp_call_function(func, info))
static inline void call_function_init(void) { }

static inline int
smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
		      void *info, int wait)
{
	return smp_call_function_single(0, func, info, wait);
}

static inline void kick_all_cpus_sync(void) {  }
static inline void wake_up_all_idle_cpus(void) {  }

#ifdef CONFIG_UP_LATE_INIT
extern void __init up_late_init(void);
static inline void smp_init(void) { up_late_init(); }
#else
static inline void smp_init(void) { }
#endif

static inline int get_boot_cpu_id(void)
{
	return 0;
}

#endif /* !SMP */

/**
 * raw_processor_id() - get the current (unstable) CPU id
 *
 * For then you know what you are doing and need an unstable
 * CPU id.
 */

/**
 * smp_processor_id() - get the current (stable) CPU id
 *
 * This is the normal accessor to the CPU id and should be used
 * whenever possible.
 *
 * The CPU id is stable when:
 *
 *  - IRQs are disabled;
 *  - preemption is disabled;
 *  - the task is CPU affine.
 *
 * When CONFIG_DEBUG_PREEMPT; we verify these assumption and WARN
 * when smp_processor_id() is used when the CPU id is not stable.
 */

/*
 * Allow the architecture to differentiate between a stable and unstable read.
 * For example, x86 uses an IRQ-safe asm-volatile read for the unstable but a
 * regular asm read for the stable.
 */
#ifndef __smp_processor_id
#define __smp_processor_id(x) raw_smp_processor_id(x)
#endif

#ifdef CONFIG_DEBUG_PREEMPT
  extern unsigned int debug_smp_processor_id(void);
# define smp_processor_id() debug_smp_processor_id()
#else
# define smp_processor_id() __smp_processor_id()
#endif

#define get_cpu()		({ preempt_disable(); __smp_processor_id(); })
#define put_cpu()		preempt_enable()

/*
 * Callback to arch code if there's nosmp or maxcpus=0 on the
 * boot command line:
 */
extern void arch_disable_smp_support(void);

extern void arch_thaw_secondary_cpus_begin(void);
extern void arch_thaw_secondary_cpus_end(void);

void smp_setup_processor_id(void);

int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par,
		    bool phys);

/* SMP core functions */
int smpcfd_prepare_cpu(unsigned int cpu);
int smpcfd_dead_cpu(unsigned int cpu);
int smpcfd_dying_cpu(unsigned int cpu);

#endif /* __LINUX_SMP_H */