include/linux/percpu.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef __LINUX_PERCPU_H
0003 #define __LINUX_PERCPU_H
0004
0005 #include <linux/mmdebug.h>
0006 #include <linux/preempt.h>
0007 #include <linux/smp.h>
0008 #include <linux/cpumask.h>
0009 #include <linux/pfn.h>
0010 #include <linux/init.h>
0011
0012 #include <asm/percpu.h>
0013
0014 /* enough to cover all DEFINE_PER_CPUs in modules */
0015 #ifdef CONFIG_MODULES
0016 #define PERCPU_MODULE_RESERVE       (8 << 10)
0017 #else
0018 #define PERCPU_MODULE_RESERVE       0
0019 #endif
0020
0021 /* minimum unit size, also is the maximum supported allocation size */
0022 #define PCPU_MIN_UNIT_SIZE      PFN_ALIGN(32 << 10)
0023
0024 /* minimum allocation size and shift in bytes */
0025 #define PCPU_MIN_ALLOC_SHIFT        2
0026 #define PCPU_MIN_ALLOC_SIZE     (1 << PCPU_MIN_ALLOC_SHIFT)
0027
0028 /*
0029  * The PCPU_BITMAP_BLOCK_SIZE must be the same size as PAGE_SIZE as the
0030  * updating of hints is used to manage the nr_empty_pop_pages in both
0031  * the chunk and globally.
0032  */
0033 #define PCPU_BITMAP_BLOCK_SIZE      PAGE_SIZE
0034 #define PCPU_BITMAP_BLOCK_BITS      (PCPU_BITMAP_BLOCK_SIZE >>  \
0035                      PCPU_MIN_ALLOC_SHIFT)
0036
0037 /*
0038  * Percpu allocator can serve percpu allocations before slab is
0039  * initialized which allows slab to depend on the percpu allocator.
0040  * The following two parameters decide how much resource to
0041  * preallocate for this.  Keep PERCPU_DYNAMIC_RESERVE equal to or
0042  * larger than PERCPU_DYNAMIC_EARLY_SIZE.
0043  */
0044 #define PERCPU_DYNAMIC_EARLY_SLOTS  128
0045 #define PERCPU_DYNAMIC_EARLY_SIZE   (12 << 10)
0046
0047 /*
0048  * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
0049  * back on the first chunk for dynamic percpu allocation if arch is
0050  * manually allocating and mapping it for faster access (as a part of
0051  * large page mapping for example).
0052  *
0053  * The following values give between one and two pages of free space
0054  * after typical minimal boot (2-way SMP, single disk and NIC) with
0055  * both defconfig and a distro config on x86_64 and 32.  More
0056  * intelligent way to determine this would be nice.
0057  */
0058 #if BITS_PER_LONG > 32
0059 #define PERCPU_DYNAMIC_RESERVE      (28 << 10)
0060 #else
0061 #define PERCPU_DYNAMIC_RESERVE      (20 << 10)
0062 #endif
0063
0064 extern void *pcpu_base_addr;
0065 extern const unsigned long *pcpu_unit_offsets;
0066
0067 struct pcpu_group_info {
0068     int         nr_units;   /* aligned # of units */
0069     unsigned long       base_offset;    /* base address offset */
0070     unsigned int        *cpu_map;   /* unit->cpu map, empty
0071                          * entries contain NR_CPUS */
0072 };
0073
0074 struct pcpu_alloc_info {
0075     size_t          static_size;
0076     size_t          reserved_size;
0077     size_t          dyn_size;
0078     size_t          unit_size;
0079     size_t          atom_size;
0080     size_t          alloc_size;
0081     size_t          __ai_size;  /* internal, don't use */
0082     int         nr_groups;  /* 0 if grouping unnecessary */
0083     struct pcpu_group_info  groups[];
0084 };
0085
0086 enum pcpu_fc {
0087     PCPU_FC_AUTO,
0088     PCPU_FC_EMBED,
0089     PCPU_FC_PAGE,
0090
0091     PCPU_FC_NR,
0092 };
0093 extern const char * const pcpu_fc_names[PCPU_FC_NR];
0094
0095 extern enum pcpu_fc pcpu_chosen_fc;
0096
0097 typedef int (pcpu_fc_cpu_to_node_fn_t)(int cpu);
0098 typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
0099
0100 extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
0101                                  int nr_units);
0102 extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
0103
0104 extern void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
0105                      void *base_addr);
0106
0107 #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
0108 extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
0109                 size_t atom_size,
0110                 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
0111                 pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);
0112 #endif
0113
0114 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
0115 void __init pcpu_populate_pte(unsigned long addr);
0116 extern int __init pcpu_page_first_chunk(size_t reserved_size,
0117                 pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);
0118 #endif
0119
0120 extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align) __alloc_size(1);
0121 extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
0122 extern bool is_kernel_percpu_address(unsigned long addr);
0123
0124 #if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
0125 extern void __init setup_per_cpu_areas(void);
0126 #endif
0127
0128 extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) __alloc_size(1);
0129 extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_size(1);
0130 extern void free_percpu(void __percpu *__pdata);
0131 extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
0132
0133 #define alloc_percpu_gfp(type, gfp)                 \
0134     (typeof(type) __percpu *)__alloc_percpu_gfp(sizeof(type),   \
0135                         __alignof__(type), gfp)
0136 #define alloc_percpu(type)                      \
0137     (typeof(type) __percpu *)__alloc_percpu(sizeof(type),       \
0138                         __alignof__(type))
0139
0140 extern unsigned long pcpu_nr_pages(void);
0141
0142 #endif /* __LINUX_PERCPU_H */