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#ifdef CONFIG_HAVE_DYNAMIC_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;
  60
  61typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno);
  62typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr);
  63
  64extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
  65                                size_t static_size, size_t reserved_size,
  66                                ssize_t dyn_size, ssize_t unit_size,
  67                                void *base_addr,
  68                                pcpu_populate_pte_fn_t populate_pte_fn);
  69
  70extern ssize_t __init pcpu_embed_first_chunk(
  71                                size_t static_size, size_t reserved_size,
  72                                ssize_t dyn_size, ssize_t unit_size);
  73
  74/*
  75 * Use this to get to a cpu's version of the per-cpu object
  76 * dynamically allocated. Non-atomic access to the current CPU's
  77 * version should probably be combined with get_cpu()/put_cpu().
  78 */
  79#define per_cpu_ptr(ptr, cpu)   SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
  80
  81extern void *__alloc_reserved_percpu(size_t size, size_t align);
  82
  83#else /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
  84
  85struct percpu_data {
  86        void *ptrs[1];
  87};
  88
  89/* pointer disguising messes up the kmemleak objects tracking */
  90#ifndef CONFIG_DEBUG_KMEMLEAK
  91#define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
  92#else
  93#define __percpu_disguise(pdata) (struct percpu_data *)(pdata)
  94#endif
  95
  96#define per_cpu_ptr(ptr, cpu)                                           \
  97({                                                                      \
  98        struct percpu_data *__p = __percpu_disguise(ptr);               \
  99        (__typeof__(ptr))__p->ptrs[(cpu)];                              \
 100})
 101
 102#endif /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
 103
 104extern void *__alloc_percpu(size_t size, size_t align);
 105extern void free_percpu(void *__pdata);
 106
 107#else /* CONFIG_SMP */
 108
 109#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
 110
 111static inline void *__alloc_percpu(size_t size, size_t align)
 112{
 113        /*
 114         * Can't easily make larger alignment work with kmalloc.  WARN
 115         * on it.  Larger alignment should only be used for module
 116         * percpu sections on SMP for which this path isn't used.
 117         */
 118        WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 119        return kzalloc(size, GFP_KERNEL);
 120}
 121
 122static inline void free_percpu(void *p)
 123{
 124        kfree(p);
 125}
 126
 127#endif /* CONFIG_SMP */
 128
 129#define alloc_percpu(type)      (type *)__alloc_percpu(sizeof(type), \
 130                                                       __alignof__(type))
 131
 132/*
 133 * Optional methods for optimized non-lvalue per-cpu variable access.
 134 *
 135 * @var can be a percpu variable or a field of it and its size should
 136 * equal char, int or long.  percpu_read() evaluates to a lvalue and
 137 * all others to void.
 138 *
 139 * These operations are guaranteed to be atomic w.r.t. preemption.
 140 * The generic versions use plain get/put_cpu_var().  Archs are
 141 * encouraged to implement single-instruction alternatives which don't
 142 * require preemption protection.
 143 */
 144#ifndef percpu_read
 145# define percpu_read(var)                                               \
 146  ({                                                                    \
 147        typeof(per_cpu_var(var)) __tmp_var__;                           \
 148        __tmp_var__ = get_cpu_var(var);                                 \
 149        put_cpu_var(var);                                               \
 150        __tmp_var__;                                                    \
 151  })
 152#endif
 153
 154#define __percpu_generic_to_op(var, val, op)                            \
 155do {                                                                    \
 156        get_cpu_var(var) op val;                                        \
 157        put_cpu_var(var);                                               \
 158} while (0)
 159
 160#ifndef percpu_write
 161# define percpu_write(var, val)         __percpu_generic_to_op(var, (val), =)
 162#endif
 163
 164#ifndef percpu_add
 165# define percpu_add(var, val)           __percpu_generic_to_op(var, (val), +=)
 166#endif
 167
 168#ifndef percpu_sub
 169# define percpu_sub(var, val)           __percpu_generic_to_op(var, (val), -=)
 170#endif
 171
 172#ifndef percpu_and
 173# define percpu_and(var, val)           __percpu_generic_to_op(var, (val), &=)
 174#endif
 175
 176#ifndef percpu_or
 177# define percpu_or(var, val)            __percpu_generic_to_op(var, (val), |=)
 178#endif
 179
 180#ifndef percpu_xor
 181# define percpu_xor(var, val)           __percpu_generic_to_op(var, (val), ^=)
 182#endif
 183
 184#endif /* __LINUX_PERCPU_H */
 185