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
  71 extern void *pcpu_base_addr;
  72 extern const unsigned long *pcpu_unit_offsets;
  73
  74 struct 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
  81 struct 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
  93 enum pcpu_fc {
  94         PCPU_FC_AUTO,
  95         PCPU_FC_EMBED,
  96         PCPU_FC_PAGE,
  97
  98         PCPU_FC_NR,
  99 };
 100 extern const char * const pcpu_fc_names[PCPU_FC_NR];
 101
 102 extern enum pcpu_fc pcpu_chosen_fc;
 103
 104 typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
 105                                      size_t align);
 106 typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
 107 typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
 108 typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
 109
 110 extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
 111                                                              int nr_units);
 112 extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
 113
 114 extern 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
 118 extern 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
 126 extern 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
 132 extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
 133 extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
 134 extern bool is_kernel_percpu_address(unsigned long addr);
 135
 136 #if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
 137 extern void __init setup_per_cpu_areas(void);
 138 #endif
 139
 140 extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
 141 extern void __percpu *__alloc_percpu(size_t size, size_t align);
 142 extern void free_percpu(void __percpu *__pdata);
 143 extern 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
 152 #endif /* __LINUX_PERCPU_H */