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 /*
  30  * The PCPU_BITMAP_BLOCK_SIZE must be the same size as PAGE_SIZE as the
  31  * updating of hints is used to manage the nr_empty_pop_pages in both
  32  * the chunk and globally.
  33  */
  34 #define PCPU_BITMAP_BLOCK_SIZE          PAGE_SIZE
  35 #define PCPU_BITMAP_BLOCK_BITS          (PCPU_BITMAP_BLOCK_SIZE >>      \
  36                                          PCPU_MIN_ALLOC_SHIFT)
  37
  38 /*
  39  * Percpu allocator can serve percpu allocations before slab is
  40  * initialized which allows slab to depend on the percpu allocator.
  41  * The following two parameters decide how much resource to
  42  * preallocate for this.  Keep PERCPU_DYNAMIC_RESERVE equal to or
  43  * larger than PERCPU_DYNAMIC_EARLY_SIZE.
  44  */
  45 #define PERCPU_DYNAMIC_EARLY_SLOTS      128
  46 #define PERCPU_DYNAMIC_EARLY_SIZE       (12 << 10)
  47
  48 /*
  49  * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
  50  * back on the first chunk for dynamic percpu allocation if arch is
  51  * manually allocating and mapping it for faster access (as a part of
  52  * large page mapping for example).
  53  *
  54  * The following values give between one and two pages of free space
  55  * after typical minimal boot (2-way SMP, single disk and NIC) with
  56  * both defconfig and a distro config on x86_64 and 32.  More
  57  * intelligent way to determine this would be nice.
  58  */
  59 #if BITS_PER_LONG > 32
  60 #define PERCPU_DYNAMIC_RESERVE          (28 << 10)
  61 #else
  62 #define PERCPU_DYNAMIC_RESERVE          (20 << 10)
  63 #endif
  64
  65 extern void *pcpu_base_addr;
  66 extern const unsigned long *pcpu_unit_offsets;
  67
  68 struct pcpu_group_info {
  69         int                     nr_units;       /* aligned # of units */
  70         unsigned long           base_offset;    /* base address offset */
  71         unsigned int            *cpu_map;       /* unit->cpu map, empty
  72                                                  * entries contain NR_CPUS */
  73 };
  74
  75 struct pcpu_alloc_info {
  76         size_t                  static_size;
  77         size_t                  reserved_size;
  78         size_t                  dyn_size;
  79         size_t                  unit_size;
  80         size_t                  atom_size;
  81         size_t                  alloc_size;
  82         size_t                  __ai_size;      /* internal, don't use */
  83         int                     nr_groups;      /* 0 if grouping unnecessary */
  84         struct pcpu_group_info  groups[];
  85 };
  86
  87 enum pcpu_fc {
  88         PCPU_FC_AUTO,
  89         PCPU_FC_EMBED,
  90         PCPU_FC_PAGE,
  91
  92         PCPU_FC_NR,
  93 };
  94 extern const char * const pcpu_fc_names[PCPU_FC_NR];
  95
  96 extern enum pcpu_fc pcpu_chosen_fc;
  97
  98 typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
  99                                      size_t align);
 100 typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
 101 typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
 102 typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
 103
 104 extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
 105                                                              int nr_units);
 106 extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
 107
 108 extern void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 109                                          void *base_addr);
 110
 111 #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
 112 extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
 113                                 size_t atom_size,
 114                                 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
 115                                 pcpu_fc_alloc_fn_t alloc_fn,
 116                                 pcpu_fc_free_fn_t free_fn);
 117 #endif
 118
 119 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
 120 extern int __init pcpu_page_first_chunk(size_t reserved_size,
 121                                 pcpu_fc_alloc_fn_t alloc_fn,
 122                                 pcpu_fc_free_fn_t free_fn,
 123                                 pcpu_fc_populate_pte_fn_t populate_pte_fn);
 124 #endif
 125
 126 extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
 127 extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
 128 extern bool is_kernel_percpu_address(unsigned long addr);
 129
 130 #if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
 131 extern void __init setup_per_cpu_areas(void);
 132 #endif
 133
 134 extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
 135 extern void __percpu *__alloc_percpu(size_t size, size_t align);
 136 extern void free_percpu(void __percpu *__pdata);
 137 extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
 138
 139 #define alloc_percpu_gfp(type, gfp)                                     \
 140         (typeof(type) __percpu *)__alloc_percpu_gfp(sizeof(type),       \
 141                                                 __alignof__(type), gfp)
 142 #define alloc_percpu(type)                                              \
 143         (typeof(type) __percpu *)__alloc_percpu(sizeof(type),           \
 144                                                 __alignof__(type))
 145
 146 extern unsigned long pcpu_nr_pages(void);
 147
 148 #endif /* __LINUX_PERCPU_H */