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
  59 extern void *pcpu_base_addr;
  60 extern const int *pcpu_unit_map;
  61
  62 typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size);
  63 typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
  64 typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
  65 typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
  66 typedef void (*pcpu_fc_map_fn_t)(void *ptr, size_t size, void *addr);
  67
  68 extern size_t __init pcpu_setup_first_chunk(
  69                                 size_t static_size, size_t reserved_size,
  70                                 ssize_t dyn_size, size_t unit_size,
  71                                 void *base_addr, const int *unit_map);
  72
  73 extern ssize_t __init pcpu_embed_first_chunk(
  74                                 size_t static_size, size_t reserved_size,
  75                                 ssize_t dyn_size);
  76
  77 extern ssize_t __init pcpu_4k_first_chunk(
  78                                 size_t static_size, size_t reserved_size,
  79                                 pcpu_fc_alloc_fn_t alloc_fn,
  80                                 pcpu_fc_free_fn_t free_fn,
  81                                 pcpu_fc_populate_pte_fn_t populate_pte_fn);
  82
  83 #ifdef CONFIG_NEED_MULTIPLE_NODES
  84 extern int __init pcpu_lpage_build_unit_map(
  85                                 size_t static_size, size_t reserved_size,
  86                                 ssize_t *dyn_sizep, size_t *unit_sizep,
  87                                 size_t lpage_size, int *unit_map,
  88                                 pcpu_fc_cpu_distance_fn_t cpu_distance_fn);
  89
  90 extern ssize_t __init pcpu_lpage_first_chunk(
  91                                 size_t static_size, size_t reserved_size,
  92                                 size_t dyn_size, size_t unit_size,
  93                                 size_t lpage_size, const int *unit_map,
  94                                 int nr_units,
  95                                 pcpu_fc_alloc_fn_t alloc_fn,
  96                                 pcpu_fc_free_fn_t free_fn,
  97                                 pcpu_fc_map_fn_t map_fn);
  98
  99 extern void *pcpu_lpage_remapped(void *kaddr);
 100 #else
 101 static inline int pcpu_lpage_build_unit_map(
 102                                 size_t static_size, size_t reserved_size,
 103                                 ssize_t *dyn_sizep, size_t *unit_sizep,
 104                                 size_t lpage_size, int *unit_map,
 105                                 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
 106 {
 107         return -EINVAL;
 108 }
 109
 110 static inline ssize_t __init pcpu_lpage_first_chunk(
 111                                 size_t static_size, size_t reserved_size,
 112                                 size_t dyn_size, size_t unit_size,
 113                                 size_t lpage_size, const int *unit_map,
 114                                 int nr_units,
 115                                 pcpu_fc_alloc_fn_t alloc_fn,
 116                                 pcpu_fc_free_fn_t free_fn,
 117                                 pcpu_fc_map_fn_t map_fn)
 118 {
 119         return -EINVAL;
 120 }
 121
 122 static inline void *pcpu_lpage_remapped(void *kaddr)
 123 {
 124         return NULL;
 125 }
 126 #endif
 127
 128 /*
 129  * Use this to get to a cpu's version of the per-cpu object
 130  * dynamically allocated. Non-atomic access to the current CPU's
 131  * version should probably be combined with get_cpu()/put_cpu().
 132  */
 133 #define per_cpu_ptr(ptr, cpu)   SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
 134
 135 extern void *__alloc_reserved_percpu(size_t size, size_t align);
 136
 137 #else /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
 138
 139 struct percpu_data {
 140         void *ptrs[1];
 141 };
 142
 143 /* pointer disguising messes up the kmemleak objects tracking */
 144 #ifndef CONFIG_DEBUG_KMEMLEAK
 145 #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
 146 #else
 147 #define __percpu_disguise(pdata) (struct percpu_data *)(pdata)
 148 #endif
 149
 150 #define per_cpu_ptr(ptr, cpu)                                           \
 151 ({                                                                      \
 152         struct percpu_data *__p = __percpu_disguise(ptr);               \
 153         (__typeof__(ptr))__p->ptrs[(cpu)];                              \
 154 })
 155
 156 #endif /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
 157
 158 extern void *__alloc_percpu(size_t size, size_t align);
 159 extern void free_percpu(void *__pdata);
 160
 161 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 162 extern void __init setup_per_cpu_areas(void);
 163 #endif
 164
 165 #else /* CONFIG_SMP */
 166
 167 #define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
 168
 169 static inline void *__alloc_percpu(size_t size, size_t align)
 170 {
 171         /*
 172          * Can't easily make larger alignment work with kmalloc.  WARN
 173          * on it.  Larger alignment should only be used for module
 174          * percpu sections on SMP for which this path isn't used.
 175          */
 176         WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 177         return kzalloc(size, GFP_KERNEL);
 178 }
 179
 180 static inline void free_percpu(void *p)
 181 {
 182         kfree(p);
 183 }
 184
 185 static inline void __init setup_per_cpu_areas(void) { }
 186
 187 #endif /* CONFIG_SMP */
 188
 189 #define alloc_percpu(type)      (type *)__alloc_percpu(sizeof(type), \
 190                                                        __alignof__(type))
 191
 192 /*
 193  * Optional methods for optimized non-lvalue per-cpu variable access.
 194  *
 195  * @var can be a percpu variable or a field of it and its size should
 196  * equal char, int or long.  percpu_read() evaluates to a lvalue and
 197  * all others to void.
 198  *
 199  * These operations are guaranteed to be atomic w.r.t. preemption.
 200  * The generic versions use plain get/put_cpu_var().  Archs are
 201  * encouraged to implement single-instruction alternatives which don't
 202  * require preemption protection.
 203  */
 204 #ifndef percpu_read
 205 # define percpu_read(var)                                               \
 206   ({                                                                    \
 207         typeof(per_cpu_var(var)) __tmp_var__;                           \
 208         __tmp_var__ = get_cpu_var(var);                                 \
 209         put_cpu_var(var);                                               \
 210         __tmp_var__;                                                    \
 211   })
 212 #endif
 213
 214 #define __percpu_generic_to_op(var, val, op)                            \
 215 do {                                                                    \
 216         get_cpu_var(var) op val;                                        \
 217         put_cpu_var(var);                                               \
 218 } while (0)
 219
 220 #ifndef percpu_write
 221 # define percpu_write(var, val)         __percpu_generic_to_op(var, (val), =)
 222 #endif
 223
 224 #ifndef percpu_add
 225 # define percpu_add(var, val)           __percpu_generic_to_op(var, (val), +=)
 226 #endif
 227
 228 #ifndef percpu_sub
 229 # define percpu_sub(var, val)           __percpu_generic_to_op(var, (val), -=)
 230 #endif
 231
 232 #ifndef percpu_and
 233 # define percpu_and(var, val)           __percpu_generic_to_op(var, (val), &=)
 234 #endif
 235
 236 #ifndef percpu_or
 237 # define percpu_or(var, val)            __percpu_generic_to_op(var, (val), |=)
 238 #endif
 239
 240 #ifndef percpu_xor
 241 # define percpu_xor(var, val)           __percpu_generic_to_op(var, (val), ^=)
 242 #endif
 243
 244 #endif /* __LINUX_PERCPU_H */