LXR linux/include/linux/percpu.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __LINUX_PERCPU_H
   3#define __LINUX_PERCPU_H
   4
   5#include <linux/mmdebug.h>
   6#include <linux/preempt.h>
   7#include <linux/smp.h>
   8#include <linux/cpumask.h>
   9#include <linux/printk.h>
  10#include <linux/pfn.h>
  11#include <linux/init.h>
  12
  13#include <asm/percpu.h>
  14
  15/* enough to cover all DEFINE_PER_CPUs in modules */
  16#ifdef CONFIG_MODULES
  17#define PERCPU_MODULE_RESERVE           (8 << 10)
  18#else
  19#define PERCPU_MODULE_RESERVE           0
  20#endif
  21
  22/* minimum unit size, also is the maximum supported allocation size */
  23#define PCPU_MIN_UNIT_SIZE              PFN_ALIGN(32 << 10)
  24
  25/* minimum allocation size and shift in bytes */
  26#define PCPU_MIN_ALLOC_SHIFT            2
  27#define PCPU_MIN_ALLOC_SIZE             (1 << PCPU_MIN_ALLOC_SHIFT)
  28
  29/* number of bits per page, used to trigger a scan if blocks are > PAGE_SIZE */
  30#define PCPU_BITS_PER_PAGE              (PAGE_SIZE >> PCPU_MIN_ALLOC_SHIFT)
  31
  32/*
  33 * This determines the size of each metadata block.  There are several subtle
  34 * constraints around this constant.  The reserved region must be a multiple of
  35 * PCPU_BITMAP_BLOCK_SIZE.  Additionally, PCPU_BITMAP_BLOCK_SIZE must be a
  36 * multiple of PAGE_SIZE or PAGE_SIZE must be a multiple of
  37 * PCPU_BITMAP_BLOCK_SIZE to align with the populated page map. The unit_size
  38 * also has to be a multiple of PCPU_BITMAP_BLOCK_SIZE to ensure full blocks.
  39 */
  40#define PCPU_BITMAP_BLOCK_SIZE          PAGE_SIZE
  41#define PCPU_BITMAP_BLOCK_BITS          (PCPU_BITMAP_BLOCK_SIZE >>      \
  42                                         PCPU_MIN_ALLOC_SHIFT)
  43
  44/*
  45 * Percpu allocator can serve percpu allocations before slab is
  46 * initialized which allows slab to depend on the percpu allocator.
  47 * The following two parameters decide how much resource to
  48 * preallocate for this.  Keep PERCPU_DYNAMIC_RESERVE equal to or
  49 * larger than PERCPU_DYNAMIC_EARLY_SIZE.
  50 */
  51#define PERCPU_DYNAMIC_EARLY_SLOTS      128
  52#define PERCPU_DYNAMIC_EARLY_SIZE       (12 << 10)
  53
  54/*
  55 * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
  56 * back on the first chunk for dynamic percpu allocation if arch is
  57 * manually allocating and mapping it for faster access (as a part of
  58 * large page mapping for example).
  59 *
  60 * The following values give between one and two pages of free space
  61 * after typical minimal boot (2-way SMP, single disk and NIC) with
  62 * both defconfig and a distro config on x86_64 and 32.  More
  63 * intelligent way to determine this would be nice.
  64 */
  65#if BITS_PER_LONG > 32
  66#define PERCPU_DYNAMIC_RESERVE          (28 << 10)
  67#else
  68#define PERCPU_DYNAMIC_RESERVE          (20 << 10)
  69#endif
  70
  71extern void *pcpu_base_addr;
  72extern const unsigned long *pcpu_unit_offsets;
  73
  74struct pcpu_group_info {
  75        int                     nr_units;       /* aligned # of units */
  76        unsigned long           base_offset;    /* base address offset */
  77        unsigned int            *cpu_map;       /* unit->cpu map, empty
  78                                                 * entries contain NR_CPUS */
  79};
  80
  81struct pcpu_alloc_info {
  82        size_t                  static_size;
  83        size_t                  reserved_size;
  84        size_t                  dyn_size;
  85        size_t                  unit_size;
  86        size_t                  atom_size;
  87        size_t                  alloc_size;
  88        size_t                  __ai_size;      /* internal, don't use */
  89        int                     nr_groups;      /* 0 if grouping unnecessary */
  90        struct pcpu_group_info  groups[];
  91};
  92
  93enum pcpu_fc {
  94        PCPU_FC_AUTO,
  95        PCPU_FC_EMBED,
  96        PCPU_FC_PAGE,
  97
  98        PCPU_FC_NR,
  99};
 100extern const char * const pcpu_fc_names[PCPU_FC_NR];
 101
 102extern enum pcpu_fc pcpu_chosen_fc;
 103
 104typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
 105                                     size_t align);
 106typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
 107typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
 108typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
 109
 110extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
 111                                                             int nr_units);
 112extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
 113
 114extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 115                                         void *base_addr);
 116
 117#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
 118extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
 119                                size_t atom_size,
 120                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
 121                                pcpu_fc_alloc_fn_t alloc_fn,
 122                                pcpu_fc_free_fn_t free_fn);
 123#endif
 124
 125#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
 126extern int __init pcpu_page_first_chunk(size_t reserved_size,
 127                                pcpu_fc_alloc_fn_t alloc_fn,
 128                                pcpu_fc_free_fn_t free_fn,
 129                                pcpu_fc_populate_pte_fn_t populate_pte_fn);
 130#endif
 131
 132extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
 133extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
 134extern bool is_kernel_percpu_address(unsigned long addr);
 135
 136#if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
 137extern void __init setup_per_cpu_areas(void);
 138#endif
 139
 140extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
 141extern void __percpu *__alloc_percpu(size_t size, size_t align);
 142extern void free_percpu(void __percpu *__pdata);
 143extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
 144
 145#define alloc_percpu_gfp(type, gfp)                                     \
 146        (typeof(type) __percpu *)__alloc_percpu_gfp(sizeof(type),       \
 147                                                __alignof__(type), gfp)
 148#define alloc_percpu(type)                                              \
 149        (typeof(type) __percpu *)__alloc_percpu(sizeof(type),           \
 150                                                __alignof__(type))
 151
 152extern unsigned long pcpu_nr_pages(void);
 153
 154#endif /* __LINUX_PERCPU_H */
 155