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 #ifndef PER_CPU_BASE_SECTION
  13 #ifdef CONFIG_SMP
  14 #define PER_CPU_BASE_SECTION ".data.percpu"
  15 #else
  16 #define PER_CPU_BASE_SECTION ".data"
  17 #endif
  18 #endif
  19
  20 #ifdef CONFIG_SMP
  21
  22 #ifdef MODULE
  23 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  24 #else
  25 #define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
  26 #endif
  27 #define PER_CPU_FIRST_SECTION ".first"
  28
  29 #else
  30
  31 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  32 #define PER_CPU_FIRST_SECTION ""
  33
  34 #endif
  35
  36 #define DEFINE_PER_CPU_SECTION(type, name, section)                     \
  37         __attribute__((__section__(PER_CPU_BASE_SECTION section)))      \
  38         PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
  39
  40 #define DEFINE_PER_CPU(type, name)                                      \
  41         DEFINE_PER_CPU_SECTION(type, name, "")
  42
  43 #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name)                       \
  44         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
  45         ____cacheline_aligned_in_smp
  46
  47 #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name)                         \
  48         DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
  49
  50 #define DEFINE_PER_CPU_FIRST(type, name)                                \
  51         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
  52
  53 #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
  54 #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
  55
  56 /* enough to cover all DEFINE_PER_CPUs in modules */
  57 #ifdef CONFIG_MODULES
  58 #define PERCPU_MODULE_RESERVE           (8 << 10)
  59 #else
  60 #define PERCPU_MODULE_RESERVE           0
  61 #endif
  62
  63 #ifndef PERCPU_ENOUGH_ROOM
  64 #define PERCPU_ENOUGH_ROOM                                              \
  65         (ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) +      \
  66          PERCPU_MODULE_RESERVE)
  67 #endif
  68
  69 /*
  70  * Must be an lvalue. Since @var must be a simple identifier,
  71  * we force a syntax error here if it isn't.
  72  */
  73 #define get_cpu_var(var) (*({                           \
  74         extern int simple_identifier_##var(void);       \
  75         preempt_disable();                              \
  76         &__get_cpu_var(var); }))
  77 #define put_cpu_var(var) preempt_enable()
  78
  79 #ifdef CONFIG_SMP
  80
  81 #ifdef CONFIG_HAVE_DYNAMIC_PER_CPU_AREA
  82
  83 /* minimum unit size, also is the maximum supported allocation size */
  84 #define PCPU_MIN_UNIT_SIZE              PFN_ALIGN(64 << 10)
  85
  86 /*
  87  * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
  88  * back on the first chunk if arch is manually allocating and mapping
  89  * it for faster access (as a part of large page mapping for example).
  90  * Note that dynamic percpu allocator covers both static and dynamic
  91  * areas, so these values are bigger than PERCPU_MODULE_RESERVE.
  92  *
  93  * On typical configuration with modules, the following values leave
  94  * about 8k of free space on the first chunk after boot on both x86_32
  95  * and 64 when module support is enabled.  When module support is
  96  * disabled, it's much tighter.
  97  */
  98 #ifndef PERCPU_DYNAMIC_RESERVE
  99 #  if BITS_PER_LONG > 32
 100 #    ifdef CONFIG_MODULES
 101 #      define PERCPU_DYNAMIC_RESERVE    (24 << 10)
 102 #    else
 103 #      define PERCPU_DYNAMIC_RESERVE    (16 << 10)
 104 #    endif
 105 #  else
 106 #    ifdef CONFIG_MODULES
 107 #      define PERCPU_DYNAMIC_RESERVE    (16 << 10)
 108 #    else
 109 #      define PERCPU_DYNAMIC_RESERVE    (8 << 10)
 110 #    endif
 111 #  endif
 112 #endif  /* PERCPU_DYNAMIC_RESERVE */
 113
 114 extern void *pcpu_base_addr;
 115
 116 typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno);
 117 typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr);
 118
 119 extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
 120                                         size_t static_size,
 121                                         ssize_t unit_size, ssize_t dyn_size,
 122                                         void *base_addr,
 123                                         pcpu_populate_pte_fn_t populate_pte_fn);
 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
 132 #else /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
 133
 134 struct percpu_data {
 135         void *ptrs[1];
 136 };
 137
 138 #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
 139
 140 #define per_cpu_ptr(ptr, cpu)                                           \
 141 ({                                                                      \
 142         struct percpu_data *__p = __percpu_disguise(ptr);               \
 143         (__typeof__(ptr))__p->ptrs[(cpu)];                              \
 144 })
 145
 146 #endif /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
 147
 148 extern void *__alloc_percpu(size_t size, size_t align);
 149 extern void free_percpu(void *__pdata);
 150
 151 #else /* CONFIG_SMP */
 152
 153 #define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
 154
 155 static inline void *__alloc_percpu(size_t size, size_t align)
 156 {
 157         /*
 158          * Can't easily make larger alignment work with kmalloc.  WARN
 159          * on it.  Larger alignment should only be used for module
 160          * percpu sections on SMP for which this path isn't used.
 161          */
 162         WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 163         return kzalloc(size, GFP_KERNEL);
 164 }
 165
 166 static inline void free_percpu(void *p)
 167 {
 168         kfree(p);
 169 }
 170
 171 #endif /* CONFIG_SMP */
 172
 173 #define alloc_percpu(type)      (type *)__alloc_percpu(sizeof(type), \
 174                                                        __alignof__(type))
 175
 176 #endif /* __LINUX_PERCPU_H */