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