include/linux/percpu-defs.h

   1 /*
   2  * linux/percpu-defs.h - basic definitions for percpu areas
   3  *
   4  * DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER.
   5  *
   6  * This file is separate from linux/percpu.h to avoid cyclic inclusion
   7  * dependency from arch header files.  Only to be included from
   8  * asm/percpu.h.
   9  *
  10  * This file includes macros necessary to declare percpu sections and
  11  * variables, and definitions of percpu accessors and operations.  It
  12  * should provide enough percpu features to arch header files even when
  13  * they can only include asm/percpu.h to avoid cyclic inclusion dependency.
  14  */
  15
  16 #ifndef _LINUX_PERCPU_DEFS_H
  17 #define _LINUX_PERCPU_DEFS_H
  18
  19 #ifdef CONFIG_SMP
  20
  21 #ifdef MODULE
  22 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  23 #define PER_CPU_ALIGNED_SECTION ""
  24 #else
  25 #define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
  26 #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
  27 #endif
  28 #define PER_CPU_FIRST_SECTION "..first"
  29
  30 #else
  31
  32 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  33 #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
  34 #define PER_CPU_FIRST_SECTION ""
  35
  36 #endif
  37
  38 /*
  39  * Base implementations of per-CPU variable declarations and definitions, where
  40  * the section in which the variable is to be placed is provided by the
  41  * 'sec' argument.  This may be used to affect the parameters governing the
  42  * variable's storage.
  43  *
  44  * NOTE!  The sections for the DECLARE and for the DEFINE must match, lest
  45  * linkage errors occur due the compiler generating the wrong code to access
  46  * that section.
  47  */
  48 #define __PCPU_ATTRS(sec)                                               \
  49         __percpu __attribute__((section(PER_CPU_BASE_SECTION sec)))     \
  50         PER_CPU_ATTRIBUTES
  51
  52 #define __PCPU_DUMMY_ATTRS                                              \
  53         __attribute__((section(".discard"), unused))
  54
  55 /*
  56  * s390 and alpha modules require percpu variables to be defined as
  57  * weak to force the compiler to generate GOT based external
  58  * references for them.  This is necessary because percpu sections
  59  * will be located outside of the usually addressable area.
  60  *
  61  * This definition puts the following two extra restrictions when
  62  * defining percpu variables.
  63  *
  64  * 1. The symbol must be globally unique, even the static ones.
  65  * 2. Static percpu variables cannot be defined inside a function.
  66  *
  67  * Archs which need weak percpu definitions should define
  68  * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
  69  *
  70  * To ensure that the generic code observes the above two
  71  * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
  72  * definition is used for all cases.
  73  */
  74 #if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
  75 /*
  76  * __pcpu_scope_* dummy variable is used to enforce scope.  It
  77  * receives the static modifier when it's used in front of
  78  * DEFINE_PER_CPU() and will trigger build failure if
  79  * DECLARE_PER_CPU() is used for the same variable.
  80  *
  81  * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
  82  * such that hidden weak symbol collision, which will cause unrelated
  83  * variables to share the same address, can be detected during build.
  84  */
  85 #define DECLARE_PER_CPU_SECTION(type, name, sec)                        \
  86         extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name;             \
  87         extern __PCPU_ATTRS(sec) __typeof__(type) name
  88
  89 #define DEFINE_PER_CPU_SECTION(type, name, sec)                         \
  90         __PCPU_DUMMY_ATTRS char __pcpu_scope_##name;                    \
  91         extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;            \
  92         __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;                   \
  93         extern __PCPU_ATTRS(sec) __typeof__(type) name;                 \
  94         __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak                 \
  95         __typeof__(type) name
  96 #else
  97 /*
  98  * Normal declaration and definition macros.
  99  */
 100 #define DECLARE_PER_CPU_SECTION(type, name, sec)                        \
 101         extern __PCPU_ATTRS(sec) __typeof__(type) name
 102
 103 #define DEFINE_PER_CPU_SECTION(type, name, sec)                         \
 104         __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES                        \
 105         __typeof__(type) name
 106 #endif
 107
 108 /*
 109  * Variant on the per-CPU variable declaration/definition theme used for
 110  * ordinary per-CPU variables.
 111  */
 112 #define DECLARE_PER_CPU(type, name)                                     \
 113         DECLARE_PER_CPU_SECTION(type, name, "")
 114
 115 #define DEFINE_PER_CPU(type, name)                                      \
 116         DEFINE_PER_CPU_SECTION(type, name, "")
 117
 118 /*
 119  * Declaration/definition used for per-CPU variables that must come first in
 120  * the set of variables.
 121  */
 122 #define DECLARE_PER_CPU_FIRST(type, name)                               \
 123         DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
 124
 125 #define DEFINE_PER_CPU_FIRST(type, name)                                \
 126         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
 127
 128 /*
 129  * Declaration/definition used for per-CPU variables that must be cacheline
 130  * aligned under SMP conditions so that, whilst a particular instance of the
 131  * data corresponds to a particular CPU, inefficiencies due to direct access by
 132  * other CPUs are reduced by preventing the data from unnecessarily spanning
 133  * cachelines.
 134  *
 135  * An example of this would be statistical data, where each CPU's set of data
 136  * is updated by that CPU alone, but the data from across all CPUs is collated
 137  * by a CPU processing a read from a proc file.
 138  */
 139 #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name)                      \
 140         DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
 141         ____cacheline_aligned_in_smp
 142
 143 #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name)                       \
 144         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
 145         ____cacheline_aligned_in_smp
 146
 147 #define DECLARE_PER_CPU_ALIGNED(type, name)                             \
 148         DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION)    \
 149         ____cacheline_aligned
 150
 151 #define DEFINE_PER_CPU_ALIGNED(type, name)                              \
 152         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION)     \
 153         ____cacheline_aligned
 154
 155 /*
 156  * Declaration/definition used for per-CPU variables that must be page aligned.
 157  */
 158 #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name)                        \
 159         DECLARE_PER_CPU_SECTION(type, name, "..page_aligned")           \
 160         __aligned(PAGE_SIZE)
 161
 162 #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name)                         \
 163         DEFINE_PER_CPU_SECTION(type, name, "..page_aligned")            \
 164         __aligned(PAGE_SIZE)
 165
 166 /*
 167  * Declaration/definition used for per-CPU variables that must be read mostly.
 168  */
 169 #define DECLARE_PER_CPU_READ_MOSTLY(type, name)                 \
 170         DECLARE_PER_CPU_SECTION(type, name, "..read_mostly")
 171
 172 #define DEFINE_PER_CPU_READ_MOSTLY(type, name)                          \
 173         DEFINE_PER_CPU_SECTION(type, name, "..read_mostly")
 174
 175 /*
 176  * Declaration/definition used for per-CPU variables that should be accessed
 177  * as decrypted when memory encryption is enabled in the guest.
 178  */
 179 #if defined(CONFIG_VIRTUALIZATION) && defined(CONFIG_AMD_MEM_ENCRYPT)
 180
 181 #define DECLARE_PER_CPU_DECRYPTED(type, name)                           \
 182         DECLARE_PER_CPU_SECTION(type, name, "..decrypted")
 183
 184 #define DEFINE_PER_CPU_DECRYPTED(type, name)                            \
 185         DEFINE_PER_CPU_SECTION(type, name, "..decrypted")
 186 #else
 187 #define DEFINE_PER_CPU_DECRYPTED(type, name)    DEFINE_PER_CPU(type, name)
 188 #endif
 189
 190 /*
 191  * Intermodule exports for per-CPU variables.  sparse forgets about
 192  * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
 193  * noop if __CHECKER__.
 194  */
 195 #ifndef __CHECKER__
 196 #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
 197 #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
 198 #else
 199 #define EXPORT_PER_CPU_SYMBOL(var)
 200 #define EXPORT_PER_CPU_SYMBOL_GPL(var)
 201 #endif
 202
 203 /*
 204  * Accessors and operations.
 205  */
 206 #ifndef __ASSEMBLY__
 207
 208 /*
 209  * __verify_pcpu_ptr() verifies @ptr is a percpu pointer without evaluating
 210  * @ptr and is invoked once before a percpu area is accessed by all
 211  * accessors and operations.  This is performed in the generic part of
 212  * percpu and arch overrides don't need to worry about it; however, if an
 213  * arch wants to implement an arch-specific percpu accessor or operation,
 214  * it may use __verify_pcpu_ptr() to verify the parameters.
 215  *
 216  * + 0 is required in order to convert the pointer type from a
 217  * potential array type to a pointer to a single item of the array.
 218  */
 219 #define __verify_pcpu_ptr(ptr)                                          \
 220 do {                                                                    \
 221         const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL;    \
 222         (void)__vpp_verify;                                             \
 223 } while (0)
 224
 225 #ifdef CONFIG_SMP
 226
 227 /*
 228  * Add an offset to a pointer but keep the pointer as-is.  Use RELOC_HIDE()
 229  * to prevent the compiler from making incorrect assumptions about the
 230  * pointer value.  The weird cast keeps both GCC and sparse happy.
 231  */
 232 #define SHIFT_PERCPU_PTR(__p, __offset)                                 \
 233         RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset))
 234
 235 #define per_cpu_ptr(ptr, cpu)                                           \
 236 ({                                                                      \
 237         __verify_pcpu_ptr(ptr);                                         \
 238         SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)));                 \
 239 })
 240
 241 #define raw_cpu_ptr(ptr)                                                \
 242 ({                                                                      \
 243         __verify_pcpu_ptr(ptr);                                         \
 244         arch_raw_cpu_ptr(ptr);                                          \
 245 })
 246
 247 #ifdef CONFIG_DEBUG_PREEMPT
 248 #define this_cpu_ptr(ptr)                                               \
 249 ({                                                                      \
 250         __verify_pcpu_ptr(ptr);                                         \
 251         SHIFT_PERCPU_PTR(ptr, my_cpu_offset);                           \
 252 })
 253 #else
 254 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
 255 #endif
 256
 257 #else   /* CONFIG_SMP */
 258
 259 #define VERIFY_PERCPU_PTR(__p)                                          \
 260 ({                                                                      \
 261         __verify_pcpu_ptr(__p);                                         \
 262         (typeof(*(__p)) __kernel __force *)(__p);                       \
 263 })
 264
 265 #define per_cpu_ptr(ptr, cpu)   ({ (void)(cpu); VERIFY_PERCPU_PTR(ptr); })
 266 #define raw_cpu_ptr(ptr)        per_cpu_ptr(ptr, 0)
 267 #define this_cpu_ptr(ptr)       raw_cpu_ptr(ptr)
 268
 269 #endif  /* CONFIG_SMP */
 270
 271 #define per_cpu(var, cpu)       (*per_cpu_ptr(&(var), cpu))
 272
 273 /*
 274  * Must be an lvalue. Since @var must be a simple identifier,
 275  * we force a syntax error here if it isn't.
 276  */
 277 #define get_cpu_var(var)                                                \
 278 (*({                                                                    \
 279         preempt_disable();                                              \
 280         this_cpu_ptr(&var);                                             \
 281 }))
 282
 283 /*
 284  * The weird & is necessary because sparse considers (void)(var) to be
 285  * a direct dereference of percpu variable (var).
 286  */
 287 #define put_cpu_var(var)                                                \
 288 do {                                                                    \
 289         (void)&(var);                                                   \
 290         preempt_enable();                                               \
 291 } while (0)
 292
 293 #define get_cpu_ptr(var)                                                \
 294 ({                                                                      \
 295         preempt_disable();                                              \
 296         this_cpu_ptr(var);                                              \
 297 })
 298
 299 #define put_cpu_ptr(var)                                                \
 300 do {                                                                    \
 301         (void)(var);                                                    \
 302         preempt_enable();                                               \
 303 } while (0)
 304
 305 /*
 306  * Branching function to split up a function into a set of functions that
 307  * are called for different scalar sizes of the objects handled.
 308  */
 309
 310 extern void __bad_size_call_parameter(void);
 311
 312 #ifdef CONFIG_DEBUG_PREEMPT
 313 extern void __this_cpu_preempt_check(const char *op);
 314 #else
 315 static inline void __this_cpu_preempt_check(const char *op) { }
 316 #endif
 317
 318 #define __pcpu_size_call_return(stem, variable)                         \
 319 ({                                                                      \
 320         typeof(variable) pscr_ret__;                                    \
 321         __verify_pcpu_ptr(&(variable));                                 \
 322         switch(sizeof(variable)) {                                      \
 323         case 1: pscr_ret__ = stem##1(variable); break;                  \
 324         case 2: pscr_ret__ = stem##2(variable); break;                  \
 325         case 4: pscr_ret__ = stem##4(variable); break;                  \
 326         case 8: pscr_ret__ = stem##8(variable); break;                  \
 327         default:                                                        \
 328                 __bad_size_call_parameter(); break;                     \
 329         }                                                               \
 330         pscr_ret__;                                                     \
 331 })
 332
 333 #define __pcpu_size_call_return2(stem, variable, ...)                   \
 334 ({                                                                      \
 335         typeof(variable) pscr2_ret__;                                   \
 336         __verify_pcpu_ptr(&(variable));                                 \
 337         switch(sizeof(variable)) {                                      \
 338         case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break;    \
 339         case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break;    \
 340         case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break;    \
 341         case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break;    \
 342         default:                                                        \
 343                 __bad_size_call_parameter(); break;                     \
 344         }                                                               \
 345         pscr2_ret__;                                                    \
 346 })
 347
 348 /*
 349  * Special handling for cmpxchg_double.  cmpxchg_double is passed two
 350  * percpu variables.  The first has to be aligned to a double word
 351  * boundary and the second has to follow directly thereafter.
 352  * We enforce this on all architectures even if they don't support
 353  * a double cmpxchg instruction, since it's a cheap requirement, and it
 354  * avoids breaking the requirement for architectures with the instruction.
 355  */
 356 #define __pcpu_double_call_return_bool(stem, pcp1, pcp2, ...)           \
 357 ({                                                                      \
 358         bool pdcrb_ret__;                                               \
 359         __verify_pcpu_ptr(&(pcp1));                                     \
 360         BUILD_BUG_ON(sizeof(pcp1) != sizeof(pcp2));                     \
 361         VM_BUG_ON((unsigned long)(&(pcp1)) % (2 * sizeof(pcp1)));       \
 362         VM_BUG_ON((unsigned long)(&(pcp2)) !=                           \
 363                   (unsigned long)(&(pcp1)) + sizeof(pcp1));             \
 364         switch(sizeof(pcp1)) {                                          \
 365         case 1: pdcrb_ret__ = stem##1(pcp1, pcp2, __VA_ARGS__); break;  \
 366         case 2: pdcrb_ret__ = stem##2(pcp1, pcp2, __VA_ARGS__); break;  \
 367         case 4: pdcrb_ret__ = stem##4(pcp1, pcp2, __VA_ARGS__); break;  \
 368         case 8: pdcrb_ret__ = stem##8(pcp1, pcp2, __VA_ARGS__); break;  \
 369         default:                                                        \
 370                 __bad_size_call_parameter(); break;                     \
 371         }                                                               \
 372         pdcrb_ret__;                                                    \
 373 })
 374
 375 #define __pcpu_size_call(stem, variable, ...)                           \
 376 do {                                                                    \
 377         __verify_pcpu_ptr(&(variable));                                 \
 378         switch(sizeof(variable)) {                                      \
 379                 case 1: stem##1(variable, __VA_ARGS__);break;           \
 380                 case 2: stem##2(variable, __VA_ARGS__);break;           \
 381                 case 4: stem##4(variable, __VA_ARGS__);break;           \
 382                 case 8: stem##8(variable, __VA_ARGS__);break;           \
 383                 default:                                                \
 384                         __bad_size_call_parameter();break;              \
 385         }                                                               \
 386 } while (0)
 387
 388 /*
 389  * this_cpu operations (C) 2008-2013 Christoph Lameter <cl@linux.com>
 390  *
 391  * Optimized manipulation for memory allocated through the per cpu
 392  * allocator or for addresses of per cpu variables.
 393  *
 394  * These operation guarantee exclusivity of access for other operations
 395  * on the *same* processor. The assumption is that per cpu data is only
 396  * accessed by a single processor instance (the current one).
 397  *
 398  * The arch code can provide optimized implementation by defining macros
 399  * for certain scalar sizes. F.e. provide this_cpu_add_2() to provide per
 400  * cpu atomic operations for 2 byte sized RMW actions. If arch code does
 401  * not provide operations for a scalar size then the fallback in the
 402  * generic code will be used.
 403  *
 404  * cmpxchg_double replaces two adjacent scalars at once.  The first two
 405  * parameters are per cpu variables which have to be of the same size.  A
 406  * truth value is returned to indicate success or failure (since a double
 407  * register result is difficult to handle).  There is very limited hardware
 408  * support for these operations, so only certain sizes may work.
 409  */
 410
 411 /*
 412  * Operations for contexts where we do not want to do any checks for
 413  * preemptions.  Unless strictly necessary, always use [__]this_cpu_*()
 414  * instead.
 415  *
 416  * If there is no other protection through preempt disable and/or disabling
 417  * interupts then one of these RMW operations can show unexpected behavior
 418  * because the execution thread was rescheduled on another processor or an
 419  * interrupt occurred and the same percpu variable was modified from the
 420  * interrupt context.
 421  */
 422 #define raw_cpu_read(pcp)               __pcpu_size_call_return(raw_cpu_read_, pcp)
 423 #define raw_cpu_write(pcp, val)         __pcpu_size_call(raw_cpu_write_, pcp, val)
 424 #define raw_cpu_add(pcp, val)           __pcpu_size_call(raw_cpu_add_, pcp, val)
 425 #define raw_cpu_and(pcp, val)           __pcpu_size_call(raw_cpu_and_, pcp, val)
 426 #define raw_cpu_or(pcp, val)            __pcpu_size_call(raw_cpu_or_, pcp, val)
 427 #define raw_cpu_add_return(pcp, val)    __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val)
 428 #define raw_cpu_xchg(pcp, nval)         __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval)
 429 #define raw_cpu_cmpxchg(pcp, oval, nval) \
 430         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
 431 #define raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
 432         __pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
 433
 434 #define raw_cpu_sub(pcp, val)           raw_cpu_add(pcp, -(val))
 435 #define raw_cpu_inc(pcp)                raw_cpu_add(pcp, 1)
 436 #define raw_cpu_dec(pcp)                raw_cpu_sub(pcp, 1)
 437 #define raw_cpu_sub_return(pcp, val)    raw_cpu_add_return(pcp, -(typeof(pcp))(val))
 438 #define raw_cpu_inc_return(pcp)         raw_cpu_add_return(pcp, 1)
 439 #define raw_cpu_dec_return(pcp)         raw_cpu_add_return(pcp, -1)
 440
 441 /*
 442  * Operations for contexts that are safe from preemption/interrupts.  These
 443  * operations verify that preemption is disabled.
 444  */
 445 #define __this_cpu_read(pcp)                                            \
 446 ({                                                                      \
 447         __this_cpu_preempt_check("read");                               \
 448         raw_cpu_read(pcp);                                              \
 449 })
 450
 451 #define __this_cpu_write(pcp, val)                                      \
 452 ({                                                                      \
 453         __this_cpu_preempt_check("write");                              \
 454         raw_cpu_write(pcp, val);                                        \
 455 })
 456
 457 #define __this_cpu_add(pcp, val)                                        \
 458 ({                                                                      \
 459         __this_cpu_preempt_check("add");                                \
 460         raw_cpu_add(pcp, val);                                          \
 461 })
 462
 463 #define __this_cpu_and(pcp, val)                                        \
 464 ({                                                                      \
 465         __this_cpu_preempt_check("and");                                \
 466         raw_cpu_and(pcp, val);                                          \
 467 })
 468
 469 #define __this_cpu_or(pcp, val)                                         \
 470 ({                                                                      \
 471         __this_cpu_preempt_check("or");                                 \
 472         raw_cpu_or(pcp, val);                                           \
 473 })
 474
 475 #define __this_cpu_add_return(pcp, val)                                 \
 476 ({                                                                      \
 477         __this_cpu_preempt_check("add_return");                         \
 478         raw_cpu_add_return(pcp, val);                                   \
 479 })
 480
 481 #define __this_cpu_xchg(pcp, nval)                                      \
 482 ({                                                                      \
 483         __this_cpu_preempt_check("xchg");                               \
 484         raw_cpu_xchg(pcp, nval);                                        \
 485 })
 486
 487 #define __this_cpu_cmpxchg(pcp, oval, nval)                             \
 488 ({                                                                      \
 489         __this_cpu_preempt_check("cmpxchg");                            \
 490         raw_cpu_cmpxchg(pcp, oval, nval);                               \
 491 })
 492
 493 #define __this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
 494 ({      __this_cpu_preempt_check("cmpxchg_double");                     \
 495         raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2); \
 496 })
 497
 498 #define __this_cpu_sub(pcp, val)        __this_cpu_add(pcp, -(typeof(pcp))(val))
 499 #define __this_cpu_inc(pcp)             __this_cpu_add(pcp, 1)
 500 #define __this_cpu_dec(pcp)             __this_cpu_sub(pcp, 1)
 501 #define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val))
 502 #define __this_cpu_inc_return(pcp)      __this_cpu_add_return(pcp, 1)
 503 #define __this_cpu_dec_return(pcp)      __this_cpu_add_return(pcp, -1)
 504
 505 /*
 506  * Operations with implied preemption/interrupt protection.  These
 507  * operations can be used without worrying about preemption or interrupt.
 508  */
 509 #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
 510 #define this_cpu_write(pcp, val)        __pcpu_size_call(this_cpu_write_, pcp, val)
 511 #define this_cpu_add(pcp, val)          __pcpu_size_call(this_cpu_add_, pcp, val)
 512 #define this_cpu_and(pcp, val)          __pcpu_size_call(this_cpu_and_, pcp, val)
 513 #define this_cpu_or(pcp, val)           __pcpu_size_call(this_cpu_or_, pcp, val)
 514 #define this_cpu_add_return(pcp, val)   __pcpu_size_call_return2(this_cpu_add_return_, pcp, val)
 515 #define this_cpu_xchg(pcp, nval)        __pcpu_size_call_return2(this_cpu_xchg_, pcp, nval)
 516 #define this_cpu_cmpxchg(pcp, oval, nval) \
 517         __pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval)
 518 #define this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
 519         __pcpu_double_call_return_bool(this_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
 520
 521 #define this_cpu_sub(pcp, val)          this_cpu_add(pcp, -(typeof(pcp))(val))
 522 #define this_cpu_inc(pcp)               this_cpu_add(pcp, 1)
 523 #define this_cpu_dec(pcp)               this_cpu_sub(pcp, 1)
 524 #define this_cpu_sub_return(pcp, val)   this_cpu_add_return(pcp, -(typeof(pcp))(val))
 525 #define this_cpu_inc_return(pcp)        this_cpu_add_return(pcp, 1)
 526 #define this_cpu_dec_return(pcp)        this_cpu_add_return(pcp, -1)
 527
 528 #endif /* __ASSEMBLY__ */
 529 #endif /* _LINUX_PERCPU_DEFS_H */