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 for dynamic percpu allocation if arch is
  89  * manually allocating and mapping it for faster access (as a part of
  90  * large page mapping for example).
  91  *
  92  * The following values give between one and two pages of free space
  93  * after typical minimal boot (2-way SMP, single disk and NIC) with
  94  * both defconfig and a distro config on x86_64 and 32.  More
  95  * intelligent way to determine this would be nice.
  96  */
  97 #if BITS_PER_LONG > 32
  98 #define PERCPU_DYNAMIC_RESERVE          (20 << 10)
  99 #else
 100 #define PERCPU_DYNAMIC_RESERVE          (12 << 10)
 101 #endif
 102
 103 extern void *pcpu_base_addr;
 104
 105 typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno);
 106 typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr);
 107
 108 extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
 109                                 size_t static_size, size_t reserved_size,
 110                                 ssize_t dyn_size, ssize_t unit_size,
 111                                 void *base_addr,
 112                                 pcpu_populate_pte_fn_t populate_pte_fn);
 113
 114 extern ssize_t __init pcpu_embed_first_chunk(
 115                                 size_t static_size, size_t reserved_size,
 116                                 ssize_t dyn_size, ssize_t unit_size);
 117
 118 /*
 119  * Use this to get to a cpu's version of the per-cpu object
 120  * dynamically allocated. Non-atomic access to the current CPU's
 121  * version should probably be combined with get_cpu()/put_cpu().
 122  */
 123 #define per_cpu_ptr(ptr, cpu)   SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
 124
 125 extern void *__alloc_reserved_percpu(size_t size, size_t align);
 126
 127 #else /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
 128
 129 struct percpu_data {
 130         void *ptrs[1];
 131 };
 132
 133 #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
 134
 135 #define per_cpu_ptr(ptr, cpu)                                           \
 136 ({                                                                      \
 137         struct percpu_data *__p = __percpu_disguise(ptr);               \
 138         (__typeof__(ptr))__p->ptrs[(cpu)];                              \
 139 })
 140
 141 #endif /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
 142
 143 extern void *__alloc_percpu(size_t size, size_t align);
 144 extern void free_percpu(void *__pdata);
 145
 146 #else /* CONFIG_SMP */
 147
 148 #define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
 149
 150 static inline void *__alloc_percpu(size_t size, size_t align)
 151 {
 152         /*
 153          * Can't easily make larger alignment work with kmalloc.  WARN
 154          * on it.  Larger alignment should only be used for module
 155          * percpu sections on SMP for which this path isn't used.
 156          */
 157         WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 158         return kzalloc(size, GFP_KERNEL);
 159 }
 160
 161 static inline void free_percpu(void *p)
 162 {
 163         kfree(p);
 164 }
 165
 166 #endif /* CONFIG_SMP */
 167
 168 #define alloc_percpu(type)      (type *)__alloc_percpu(sizeof(type), \
 169                                                        __alignof__(type))
 170
 171 /*
 172  * Optional methods for optimized non-lvalue per-cpu variable access.
 173  *
 174  * @var can be a percpu variable or a field of it and its size should
 175  * equal char, int or long.  percpu_read() evaluates to a lvalue and
 176  * all others to void.
 177  *
 178  * These operations are guaranteed to be atomic w.r.t. preemption.
 179  * The generic versions use plain get/put_cpu_var().  Archs are
 180  * encouraged to implement single-instruction alternatives which don't
 181  * require preemption protection.
 182  */
 183 #ifndef percpu_read
 184 # define percpu_read(var)                                               \
 185   ({                                                                    \
 186         typeof(per_cpu_var(var)) __tmp_var__;                           \
 187         __tmp_var__ = get_cpu_var(var);                                 \
 188         put_cpu_var(var);                                               \
 189         __tmp_var__;                                                    \
 190   })
 191 #endif
 192
 193 #define __percpu_generic_to_op(var, val, op)                            \
 194 do {                                                                    \
 195         get_cpu_var(var) op val;                                        \
 196         put_cpu_var(var);                                               \
 197 } while (0)
 198
 199 #ifndef percpu_write
 200 # define percpu_write(var, val)         __percpu_generic_to_op(var, (val), =)
 201 #endif
 202
 203 #ifndef percpu_add
 204 # define percpu_add(var, val)           __percpu_generic_to_op(var, (val), +=)
 205 #endif
 206
 207 #ifndef percpu_sub
 208 # define percpu_sub(var, val)           __percpu_generic_to_op(var, (val), -=)
 209 #endif
 210
 211 #ifndef percpu_and
 212 # define percpu_and(var, val)           __percpu_generic_to_op(var, (val), &=)
 213 #endif
 214
 215 #ifndef percpu_or
 216 # define percpu_or(var, val)            __percpu_generic_to_op(var, (val), |=)
 217 #endif
 218
 219 #ifndef percpu_xor
 220 # define percpu_xor(var, val)           __percpu_generic_to_op(var, (val), ^=)
 221 #endif
 222
 223 #endif /* __LINUX_PERCPU_H */