root/include/linux/percpu.h

INCLUDED FROM

#ifndef __LINUX_PERCPU_H
#define __LINUX_PERCPU_H

#include <linux/mmdebug.h>
#include <linux/preempt.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/pfn.h>
#include <linux/init.h>

#include <asm/percpu.h>

/* enough to cover all DEFINE_PER_CPUs in modules */
#ifdef CONFIG_MODULES
#define PERCPU_MODULE_RESERVE           (8 << 10)
#else
#define PERCPU_MODULE_RESERVE           0
#endif

#ifndef PERCPU_ENOUGH_ROOM
#define PERCPU_ENOUGH_ROOM                                              \
        (ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) +      \
         PERCPU_MODULE_RESERVE)
#endif

/* minimum unit size, also is the maximum supported allocation size */
#define PCPU_MIN_UNIT_SIZE              PFN_ALIGN(32 << 10)

/*
 * Percpu allocator can serve percpu allocations before slab is
 * initialized which allows slab to depend on the percpu allocator.
 * The following two parameters decide how much resource to
 * preallocate for this.  Keep PERCPU_DYNAMIC_RESERVE equal to or
 * larger than PERCPU_DYNAMIC_EARLY_SIZE.
 */
#define PERCPU_DYNAMIC_EARLY_SLOTS      128
#define PERCPU_DYNAMIC_EARLY_SIZE       (12 << 10)

/*
 * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
 * back on the first chunk for dynamic percpu allocation if arch is
 * manually allocating and mapping it for faster access (as a part of
 * large page mapping for example).
 *
 * The following values give between one and two pages of free space
 * after typical minimal boot (2-way SMP, single disk and NIC) with
 * both defconfig and a distro config on x86_64 and 32.  More
 * intelligent way to determine this would be nice.
 */
#if BITS_PER_LONG > 32
#define PERCPU_DYNAMIC_RESERVE          (28 << 10)
#else
#define PERCPU_DYNAMIC_RESERVE          (20 << 10)
#endif

extern void *pcpu_base_addr;
extern const unsigned long *pcpu_unit_offsets;

struct pcpu_group_info {
        int                     nr_units;       /* aligned # of units */
        unsigned long           base_offset;    /* base address offset */
        unsigned int            *cpu_map;       /* unit->cpu map, empty
                                                 * entries contain NR_CPUS */
};

struct pcpu_alloc_info {
        size_t                  static_size;
        size_t                  reserved_size;
        size_t                  dyn_size;
        size_t                  unit_size;
        size_t                  atom_size;
        size_t                  alloc_size;
        size_t                  __ai_size;      /* internal, don't use */
        int                     nr_groups;      /* 0 if grouping unnecessary */
        struct pcpu_group_info  groups[];
};

enum pcpu_fc {
        PCPU_FC_AUTO,
        PCPU_FC_EMBED,
        PCPU_FC_PAGE,

        PCPU_FC_NR,
};
extern const char * const pcpu_fc_names[PCPU_FC_NR];

extern enum pcpu_fc pcpu_chosen_fc;

typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
                                     size_t align);
typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);

extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
                                                             int nr_units);
extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);

extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
                                         void *base_addr);

#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
                                size_t atom_size,
                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
                                pcpu_fc_alloc_fn_t alloc_fn,
                                pcpu_fc_free_fn_t free_fn);
#endif

#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
extern int __init pcpu_page_first_chunk(size_t reserved_size,
                                pcpu_fc_alloc_fn_t alloc_fn,
                                pcpu_fc_free_fn_t free_fn,
                                pcpu_fc_populate_pte_fn_t populate_pte_fn);
#endif

extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
extern bool is_kernel_percpu_address(unsigned long addr);

#if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
extern void __init setup_per_cpu_areas(void);
#endif
extern void __init percpu_init_late(void);

extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
extern void __percpu *__alloc_percpu(size_t size, size_t align);
extern void free_percpu(void __percpu *__pdata);
extern phys_addr_t per_cpu_ptr_to_phys(void *addr);

#define alloc_percpu_gfp(type, gfp)                                     \
        (typeof(type) __percpu *)__alloc_percpu_gfp(sizeof(type),       \
                                                __alignof__(type), gfp)
#define alloc_percpu(type)                                              \
        (typeof(type) __percpu *)__alloc_percpu(sizeof(type),           \
                                                __alignof__(type))

#endif /* __LINUX_PERCPU_H */