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 unsigned long *pcpu_unit_offsets;
  61
  62 struct pcpu_group_info {
  63         int                     nr_units;       /* aligned # of units */
  64         unsigned long           base_offset;    /* base address offset */
  65         unsigned int            *cpu_map;       /* unit->cpu map, empty
  66                                                  * entries contain NR_CPUS */
  67 };
  68
  69 struct pcpu_alloc_info {
  70         size_t                  static_size;
  71         size_t                  reserved_size;
  72         size_t                  dyn_size;
  73         size_t                  unit_size;
  74         size_t                  atom_size;
  75         size_t                  alloc_size;
  76         size_t                  __ai_size;      /* internal, don't use */
  77         int                     nr_groups;      /* 0 if grouping unnecessary */
  78         struct pcpu_group_info  groups[];
  79 };
  80
  81 enum pcpu_fc {
  82         PCPU_FC_AUTO,
  83         PCPU_FC_EMBED,
  84         PCPU_FC_PAGE,
  85
  86         PCPU_FC_NR,
  87 };
  88 extern const char *pcpu_fc_names[PCPU_FC_NR];
  89
  90 extern enum pcpu_fc pcpu_chosen_fc;
  91
  92 typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size,
  93                                      size_t align);
  94 typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
  95 typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);
  96 typedef int (pcpu_fc_cpu_distance_fn_t)(unsigned int from, unsigned int to);
  97
  98 extern struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
  99                                                              int nr_units);
 100 extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);
 101
 102 extern struct pcpu_alloc_info * __init pcpu_build_alloc_info(
 103                                 size_t reserved_size, ssize_t dyn_size,
 104                                 size_t atom_size,
 105                                 pcpu_fc_cpu_distance_fn_t cpu_distance_fn);
 106
 107 extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 108                                          void *base_addr);
 109
 110 #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
 111 extern int __init pcpu_embed_first_chunk(size_t reserved_size, ssize_t dyn_size,
 112                                 size_t atom_size,
 113                                 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
 114                                 pcpu_fc_alloc_fn_t alloc_fn,
 115                                 pcpu_fc_free_fn_t free_fn);
 116 #endif
 117
 118 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
 119 extern int __init pcpu_page_first_chunk(size_t reserved_size,
 120                                 pcpu_fc_alloc_fn_t alloc_fn,
 121                                 pcpu_fc_free_fn_t free_fn,
 122                                 pcpu_fc_populate_pte_fn_t populate_pte_fn);
 123 #endif
 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 extern void *__alloc_reserved_percpu(size_t size, size_t align);
 133
 134 #else /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
 135
 136 struct percpu_data {
 137         void *ptrs[1];
 138 };
 139
 140 /* pointer disguising messes up the kmemleak objects tracking */
 141 #ifndef CONFIG_DEBUG_KMEMLEAK
 142 #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
 143 #else
 144 #define __percpu_disguise(pdata) (struct percpu_data *)(pdata)
 145 #endif
 146
 147 #define per_cpu_ptr(ptr, cpu)                                           \
 148 ({                                                                      \
 149         struct percpu_data *__p = __percpu_disguise(ptr);               \
 150         (__typeof__(ptr))__p->ptrs[(cpu)];                              \
 151 })
 152
 153 #endif /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
 154
 155 extern void *__alloc_percpu(size_t size, size_t align);
 156 extern void free_percpu(void *__pdata);
 157
 158 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 159 extern void __init setup_per_cpu_areas(void);
 160 #endif
 161
 162 #else /* CONFIG_SMP */
 163
 164 #define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
 165
 166 static inline void *__alloc_percpu(size_t size, size_t align)
 167 {
 168         /*
 169          * Can't easily make larger alignment work with kmalloc.  WARN
 170          * on it.  Larger alignment should only be used for module
 171          * percpu sections on SMP for which this path isn't used.
 172          */
 173         WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 174         return kzalloc(size, GFP_KERNEL);
 175 }
 176
 177 static inline void free_percpu(void *p)
 178 {
 179         kfree(p);
 180 }
 181
 182 static inline void __init setup_per_cpu_areas(void) { }
 183
 184 static inline void *pcpu_lpage_remapped(void *kaddr)
 185 {
 186         return NULL;
 187 }
 188
 189 #endif /* CONFIG_SMP */
 190
 191 #define alloc_percpu(type)      (type *)__alloc_percpu(sizeof(type), \
 192                                                        __alignof__(type))
 193
 194 /*
 195  * Optional methods for optimized non-lvalue per-cpu variable access.
 196  *
 197  * @var can be a percpu variable or a field of it and its size should
 198  * equal char, int or long.  percpu_read() evaluates to a lvalue and
 199  * all others to void.
 200  *
 201  * These operations are guaranteed to be atomic w.r.t. preemption.
 202  * The generic versions use plain get/put_cpu_var().  Archs are
 203  * encouraged to implement single-instruction alternatives which don't
 204  * require preemption protection.
 205  */
 206 #ifndef percpu_read
 207 # define percpu_read(var)                                               \
 208   ({                                                                    \
 209         typeof(per_cpu_var(var)) __tmp_var__;                           \
 210         __tmp_var__ = get_cpu_var(var);                                 \
 211         put_cpu_var(var);                                               \
 212         __tmp_var__;                                                    \
 213   })
 214 #endif
 215
 216 #define __percpu_generic_to_op(var, val, op)                            \
 217 do {                                                                    \
 218         get_cpu_var(var) op val;                                        \
 219         put_cpu_var(var);                                               \
 220 } while (0)
 221
 222 #ifndef percpu_write
 223 # define percpu_write(var, val)         __percpu_generic_to_op(var, (val), =)
 224 #endif
 225
 226 #ifndef percpu_add
 227 # define percpu_add(var, val)           __percpu_generic_to_op(var, (val), +=)
 228 #endif
 229
 230 #ifndef percpu_sub
 231 # define percpu_sub(var, val)           __percpu_generic_to_op(var, (val), -=)
 232 #endif
 233
 234 #ifndef percpu_and
 235 # define percpu_and(var, val)           __percpu_generic_to_op(var, (val), &=)
 236 #endif
 237
 238 #ifndef percpu_or
 239 # define percpu_or(var, val)            __percpu_generic_to_op(var, (val), |=)
 240 #endif
 241
 242 #ifndef percpu_xor
 243 # define percpu_xor(var, val)           __percpu_generic_to_op(var, (val), ^=)
 244 #endif
 245
 246 #endif /* __LINUX_PERCPU_H */