LXR linux/include/linux/percpu.h

   1#ifndef __LINUX_PERCPU_H
   2#define __LINUX_PERCPU_H
   3
   4#include <linux/preempt.h>
   5#include <linux/slab.h> /* For kmalloc() */
   6#include <linux/smp.h>
   7#include <linux/cpumask.h>
   8#include <linux/pfn.h>
   9
  10#include <asm/percpu.h>
  11
  12/* enough to cover all DEFINE_PER_CPUs in modules */
  13#ifdef CONFIG_MODULES
  14#define PERCPU_MODULE_RESERVE           (8 << 10)
  15#else
  16#define PERCPU_MODULE_RESERVE           0
  17#endif
  18
  19#ifndef PERCPU_ENOUGH_ROOM
  20#define PERCPU_ENOUGH_ROOM                                              \
  21        (ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) +      \
  22         PERCPU_MODULE_RESERVE)
  23#endif
  24
  25/*
  26 * Must be an lvalue. Since @var must be a simple identifier,
  27 * we force a syntax error here if it isn't.
  28 */
  29#define get_cpu_var(var) (*({                           \
  30        extern int simple_identifier_##var(void);       \
  31        preempt_disable();                              \
  32        &__get_cpu_var(var); }))
  33#define put_cpu_var(var) preempt_enable()
  34
  35#ifdef CONFIG_SMP
  36
  37#ifndef CONFIG_HAVE_LEGACY_PER_CPU_AREA
  38
  39/* minimum unit size, also is the maximum supported allocation size */
  40#define PCPU_MIN_UNIT_SIZE              PFN_ALIGN(64 << 10)
  41
  42/*
  43 * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
  44 * back on the first chunk for dynamic percpu allocation if arch is
  45 * manually allocating and mapping it for faster access (as a part of
  46 * large page mapping for example).
  47 *
  48 * The following values give between one and two pages of free space
  49 * after typical minimal boot (2-way SMP, single disk and NIC) with
  50 * both defconfig and a distro config on x86_64 and 32.  More
  51 * intelligent way to determine this would be nice.
  52 */
  53#if BITS_PER_LONG > 32
  54#define PERCPU_DYNAMIC_RESERVE          (20 << 10)
  55#else
  56#define PERCPU_DYNAMIC_RESERVE          (12 << 10)
  57#endif
  58
  59extern void *pcpu_base_addr;
  60extern const unsigned long *pcpu_unit_offsets;
  61
  62struct pcpu_group_info {
  63        int                     nr_units;       /* aligned # of units */
  64        unsigned long           base_offset;    /* base address offset */
  65        unsigned int            *cpu_map;       /* unit->cpu map, empty
  66                                                 * entries contain NR_CPUS */
  67};
  68
  69struct pcpu_alloc_info {
  70        size_t                  static_size;
  71        size_t                  reserved_size;
  72        size_t                  dyn_size;
  73        size_t                  unit_size;
  74        size_t                  atom_size;
  75        size_t                  alloc_size;
  76        size_t                  __ai_size;      /* internal, don't use */
  77        int                     nr_groups;      /* 0 if grouping unnecessary */
  78        struct pcpu_group_info  groups[];
  79};
  80
  81enum pcpu_fc {
  82        PCPU_FC_AUTO,
  83        PCPU_FC_EMBED,
  84        PCPU_FC_PAGE,
  85
  86        PCPU_FC_NR,
  87};
  88extern const char *pcpu_fc_names[PCPU_FC_NR];
  89
  90extern enum pcpu_fc pcpu_chosen_fc;
  91
  92typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
  93                                     size_t align);
  94typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
  95typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
  96typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
  97
  98extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
  99                                                             int nr_units);
 100extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
 101
 102extern struct pcpu_alloc_info * __init pcpu_build_alloc_info(
 103                                size_t reserved_size, ssize_t dyn_size,
 104                                size_t atom_size,
 105                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn);
 106
 107extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 108                                         void *base_addr);
 109
 110#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
 111extern int __init pcpu_embed_first_chunk(size_t reserved_size, ssize_t dyn_size,
 112                                size_t atom_size,
 113                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
 114                                pcpu_fc_alloc_fn_t alloc_fn,
 115                                pcpu_fc_free_fn_t free_fn);
 116#endif
 117
 118#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
 119extern int __init pcpu_page_first_chunk(size_t reserved_size,
 120                                pcpu_fc_alloc_fn_t alloc_fn,
 121                                pcpu_fc_free_fn_t free_fn,
 122                                pcpu_fc_populate_pte_fn_t populate_pte_fn);
 123#endif
 124
 125/*
 126 * Use this to get to a cpu's version of the per-cpu object
 127 * dynamically allocated. Non-atomic access to the current CPU's
 128 * version should probably be combined with get_cpu()/put_cpu().
 129 */
 130#define per_cpu_ptr(ptr, cpu)   SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
 131
 132extern void *__alloc_reserved_percpu(size_t size, size_t align);
 133
 134#else /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
 135
 136struct percpu_data {
 137        void *ptrs[1];
 138};
 139
 140/* pointer disguising messes up the kmemleak objects tracking */
 141#ifndef CONFIG_DEBUG_KMEMLEAK
 142#define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
 143#else
 144#define __percpu_disguise(pdata) (struct percpu_data *)(pdata)
 145#endif
 146
 147#define per_cpu_ptr(ptr, cpu)                                           \
 148({                                                                      \
 149        struct percpu_data *__p = __percpu_disguise(ptr);               \
 150        (__typeof__(ptr))__p->ptrs[(cpu)];                              \
 151})
 152
 153#endif /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
 154
 155extern void *__alloc_percpu(size_t size, size_t align);
 156extern void free_percpu(void *__pdata);
 157
 158#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 159extern void __init setup_per_cpu_areas(void);
 160#endif
 161
 162#else /* CONFIG_SMP */
 163
 164#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
 165
 166static inline void *__alloc_percpu(size_t size, size_t align)
 167{
 168        /*
 169         * Can't easily make larger alignment work with kmalloc.  WARN
 170         * on it.  Larger alignment should only be used for module
 171         * percpu sections on SMP for which this path isn't used.
 172         */
 173        WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 174        return kzalloc(size, GFP_KERNEL);
 175}
 176
 177static inline void free_percpu(void *p)
 178{
 179        kfree(p);
 180}
 181
 182static inline void __init setup_per_cpu_areas(void) { }
 183
 184static inline void *pcpu_lpage_remapped(void *kaddr)
 185{
 186        return NULL;
 187}
 188
 189#endif /* CONFIG_SMP */
 190
 191#define alloc_percpu(type)      (type *)__alloc_percpu(sizeof(type), \
 192                                                       __alignof__(type))
 193
 194/*
 195 * Optional methods for optimized non-lvalue per-cpu variable access.
 196 *
 197 * @var can be a percpu variable or a field of it and its size should
 198 * equal char, int or long.  percpu_read() evaluates to a lvalue and
 199 * all others to void.
 200 *
 201 * These operations are guaranteed to be atomic w.r.t. preemption.
 202 * The generic versions use plain get/put_cpu_var().  Archs are
 203 * encouraged to implement single-instruction alternatives which don't
 204 * require preemption protection.
 205 */
 206#ifndef percpu_read
 207# define percpu_read(var)                                               \
 208  ({                                                                    \
 209        typeof(per_cpu_var(var)) __tmp_var__;                           \
 210        __tmp_var__ = get_cpu_var(var);                                 \
 211        put_cpu_var(var);                                               \
 212        __tmp_var__;                                                    \
 213  })
 214#endif
 215
 216#define __percpu_generic_to_op(var, val, op)                            \
 217do {                                                                    \
 218        get_cpu_var(var) op val;                                        \
 219        put_cpu_var(var);                                               \
 220} while (0)
 221
 222#ifndef percpu_write
 223# define percpu_write(var, val)         __percpu_generic_to_op(var, (val), =)
 224#endif
 225
 226#ifndef percpu_add
 227# define percpu_add(var, val)           __percpu_generic_to_op(var, (val), +=)
 228#endif
 229
 230#ifndef percpu_sub
 231# define percpu_sub(var, val)           __percpu_generic_to_op(var, (val), -=)
 232#endif
 233
 234#ifndef percpu_and
 235# define percpu_and(var, val)           __percpu_generic_to_op(var, (val), &=)
 236#endif
 237
 238#ifndef percpu_or
 239# define percpu_or(var, val)            __percpu_generic_to_op(var, (val), |=)
 240#endif
 241
 242#ifndef percpu_xor
 243# define percpu_xor(var, val)           __percpu_generic_to_op(var, (val), ^=)
 244#endif
 245
 246#endif /* __LINUX_PERCPU_H */
 247