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