LCOV - code coverage report
Current view: top level - include/linux - percpu-defs.h (source / functions) Hit Total Coverage
Test: combined.info Lines: 1 1 100.0 %
Date: 2022-04-01 13:59:58 Functions: 0 0 -
Branches: 22 34 64.7 %

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0-only */
       2                 :            : /*
       3                 :            :  * linux/percpu-defs.h - basic definitions for percpu areas
       4                 :            :  *
       5                 :            :  * DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER.
       6                 :            :  *
       7                 :            :  * This file is separate from linux/percpu.h to avoid cyclic inclusion
       8                 :            :  * dependency from arch header files.  Only to be included from
       9                 :            :  * asm/percpu.h.
      10                 :            :  *
      11                 :            :  * This file includes macros necessary to declare percpu sections and
      12                 :            :  * variables, and definitions of percpu accessors and operations.  It
      13                 :            :  * should provide enough percpu features to arch header files even when
      14                 :            :  * they can only include asm/percpu.h to avoid cyclic inclusion dependency.
      15                 :            :  */
      16                 :            : 
      17                 :            : #ifndef _LINUX_PERCPU_DEFS_H
      18                 :            : #define _LINUX_PERCPU_DEFS_H
      19                 :            : 
      20                 :            : #ifdef CONFIG_SMP
      21                 :            : 
      22                 :            : #ifdef MODULE
      23                 :            : #define PER_CPU_SHARED_ALIGNED_SECTION ""
      24                 :            : #define PER_CPU_ALIGNED_SECTION ""
      25                 :            : #else
      26                 :            : #define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
      27                 :            : #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
      28                 :            : #endif
      29                 :            : #define PER_CPU_FIRST_SECTION "..first"
      30                 :            : 
      31                 :            : #else
      32                 :            : 
      33                 :            : #define PER_CPU_SHARED_ALIGNED_SECTION ""
      34                 :            : #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
      35                 :            : #define PER_CPU_FIRST_SECTION ""
      36                 :            : 
      37                 :            : #endif
      38                 :            : 
      39                 :            : /*
      40                 :            :  * Base implementations of per-CPU variable declarations and definitions, where
      41                 :            :  * the section in which the variable is to be placed is provided by the
      42                 :            :  * 'sec' argument.  This may be used to affect the parameters governing the
      43                 :            :  * variable's storage.
      44                 :            :  *
      45                 :            :  * NOTE!  The sections for the DECLARE and for the DEFINE must match, lest
      46                 :            :  * linkage errors occur due the compiler generating the wrong code to access
      47                 :            :  * that section.
      48                 :            :  */
      49                 :            : #define __PCPU_ATTRS(sec)                                               \
      50                 :            :         __percpu __attribute__((section(PER_CPU_BASE_SECTION sec)))     \
      51                 :            :         PER_CPU_ATTRIBUTES
      52                 :            : 
      53                 :            : #define __PCPU_DUMMY_ATTRS                                              \
      54                 :            :         __attribute__((section(".discard"), unused))
      55                 :            : 
      56                 :            : /*
      57                 :            :  * s390 and alpha modules require percpu variables to be defined as
      58                 :            :  * weak to force the compiler to generate GOT based external
      59                 :            :  * references for them.  This is necessary because percpu sections
      60                 :            :  * will be located outside of the usually addressable area.
      61                 :            :  *
      62                 :            :  * This definition puts the following two extra restrictions when
      63                 :            :  * defining percpu variables.
      64                 :            :  *
      65                 :            :  * 1. The symbol must be globally unique, even the static ones.
      66                 :            :  * 2. Static percpu variables cannot be defined inside a function.
      67                 :            :  *
      68                 :            :  * Archs which need weak percpu definitions should define
      69                 :            :  * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
      70                 :            :  *
      71                 :            :  * To ensure that the generic code observes the above two
      72                 :            :  * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
      73                 :            :  * definition is used for all cases.
      74                 :            :  */
      75                 :            : #if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
      76                 :            : /*
      77                 :            :  * __pcpu_scope_* dummy variable is used to enforce scope.  It
      78                 :            :  * receives the static modifier when it's used in front of
      79                 :            :  * DEFINE_PER_CPU() and will trigger build failure if
      80                 :            :  * DECLARE_PER_CPU() is used for the same variable.
      81                 :            :  *
      82                 :            :  * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
      83                 :            :  * such that hidden weak symbol collision, which will cause unrelated
      84                 :            :  * variables to share the same address, can be detected during build.
      85                 :            :  */
      86                 :            : #define DECLARE_PER_CPU_SECTION(type, name, sec)                        \
      87                 :            :         extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name;             \
      88                 :            :         extern __PCPU_ATTRS(sec) __typeof__(type) name
      89                 :            : 
      90                 :            : #define DEFINE_PER_CPU_SECTION(type, name, sec)                         \
      91                 :            :         __PCPU_DUMMY_ATTRS char __pcpu_scope_##name;                    \
      92                 :            :         extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;            \
      93                 :            :         __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;                   \
      94                 :            :         extern __PCPU_ATTRS(sec) __typeof__(type) name;                 \
      95                 :            :         __PCPU_ATTRS(sec) __weak __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) __typeof__(type) name
     105                 :            : #endif
     106                 :            : 
     107                 :            : /*
     108                 :            :  * Variant on the per-CPU variable declaration/definition theme used for
     109                 :            :  * ordinary per-CPU variables.
     110                 :            :  */
     111                 :            : #define DECLARE_PER_CPU(type, name)                                     \
     112                 :            :         DECLARE_PER_CPU_SECTION(type, name, "")
     113                 :            : 
     114                 :            : #define DEFINE_PER_CPU(type, name)                                      \
     115                 :            :         DEFINE_PER_CPU_SECTION(type, name, "")
     116                 :            : 
     117                 :            : /*
     118                 :            :  * Declaration/definition used for per-CPU variables that must come first in
     119                 :            :  * the set of variables.
     120                 :            :  */
     121                 :            : #define DECLARE_PER_CPU_FIRST(type, name)                               \
     122                 :            :         DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
     123                 :            : 
     124                 :            : #define DEFINE_PER_CPU_FIRST(type, name)                                \
     125                 :            :         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
     126                 :            : 
     127                 :            : /*
     128                 :            :  * Declaration/definition used for per-CPU variables that must be cacheline
     129                 :            :  * aligned under SMP conditions so that, whilst a particular instance of the
     130                 :            :  * data corresponds to a particular CPU, inefficiencies due to direct access by
     131                 :            :  * other CPUs are reduced by preventing the data from unnecessarily spanning
     132                 :            :  * cachelines.
     133                 :            :  *
     134                 :            :  * An example of this would be statistical data, where each CPU's set of data
     135                 :            :  * is updated by that CPU alone, but the data from across all CPUs is collated
     136                 :            :  * by a CPU processing a read from a proc file.
     137                 :            :  */
     138                 :            : #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name)                      \
     139                 :            :         DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
     140                 :            :         ____cacheline_aligned_in_smp
     141                 :            : 
     142                 :            : #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name)                       \
     143                 :            :         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
     144                 :            :         ____cacheline_aligned_in_smp
     145                 :            : 
     146                 :            : #define DECLARE_PER_CPU_ALIGNED(type, name)                             \
     147                 :            :         DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION)    \
     148                 :            :         ____cacheline_aligned
     149                 :            : 
     150                 :            : #define DEFINE_PER_CPU_ALIGNED(type, name)                              \
     151                 :            :         DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION)     \
     152                 :            :         ____cacheline_aligned
     153                 :            : 
     154                 :            : /*
     155                 :            :  * Declaration/definition used for per-CPU variables that must be page aligned.
     156                 :            :  */
     157                 :            : #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name)                        \
     158                 :            :         DECLARE_PER_CPU_SECTION(type, name, "..page_aligned")         \
     159                 :            :         __aligned(PAGE_SIZE)
     160                 :            : 
     161                 :            : #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name)                         \
     162                 :            :         DEFINE_PER_CPU_SECTION(type, name, "..page_aligned")          \
     163                 :            :         __aligned(PAGE_SIZE)
     164                 :            : 
     165                 :            : /*
     166                 :            :  * Declaration/definition used for per-CPU variables that must be read mostly.
     167                 :            :  */
     168                 :            : #define DECLARE_PER_CPU_READ_MOSTLY(type, name)                 \
     169                 :            :         DECLARE_PER_CPU_SECTION(type, name, "..read_mostly")
     170                 :            : 
     171                 :            : #define DEFINE_PER_CPU_READ_MOSTLY(type, name)                          \
     172                 :            :         DEFINE_PER_CPU_SECTION(type, name, "..read_mostly")
     173                 :            : 
     174                 :            : /*
     175                 :            :  * Declaration/definition used for per-CPU variables that should be accessed
     176                 :            :  * as decrypted when memory encryption is enabled in the guest.
     177                 :            :  */
     178                 :            : #ifdef CONFIG_AMD_MEM_ENCRYPT
     179                 :            : #define DECLARE_PER_CPU_DECRYPTED(type, name)                           \
     180                 :            :         DECLARE_PER_CPU_SECTION(type, name, "..decrypted")
     181                 :            : 
     182                 :            : #define DEFINE_PER_CPU_DECRYPTED(type, name)                            \
     183                 :            :         DEFINE_PER_CPU_SECTION(type, name, "..decrypted")
     184                 :            : #else
     185                 :            : #define DEFINE_PER_CPU_DECRYPTED(type, name)    DEFINE_PER_CPU(type, name)
     186                 :            : #endif
     187                 :            : 
     188                 :            : /*
     189                 :            :  * Intermodule exports for per-CPU variables.  sparse forgets about
     190                 :            :  * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
     191                 :            :  * noop if __CHECKER__.
     192                 :            :  */
     193                 :            : #ifndef __CHECKER__
     194                 :            : #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
     195                 :            : #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
     196                 :            : #else
     197                 :            : #define EXPORT_PER_CPU_SYMBOL(var)
     198                 :            : #define EXPORT_PER_CPU_SYMBOL_GPL(var)
     199                 :            : #endif
     200                 :            : 
     201                 :            : /*
     202                 :            :  * Accessors and operations.
     203                 :            :  */
     204                 :            : #ifndef __ASSEMBLY__
     205                 :            : 
     206                 :            : /*
     207                 :            :  * __verify_pcpu_ptr() verifies @ptr is a percpu pointer without evaluating
     208                 :            :  * @ptr and is invoked once before a percpu area is accessed by all
     209                 :            :  * accessors and operations.  This is performed in the generic part of
     210                 :            :  * percpu and arch overrides don't need to worry about it; however, if an
     211                 :            :  * arch wants to implement an arch-specific percpu accessor or operation,
     212                 :            :  * it may use __verify_pcpu_ptr() to verify the parameters.
     213                 :            :  *
     214                 :            :  * + 0 is required in order to convert the pointer type from a
     215                 :            :  * potential array type to a pointer to a single item of the array.
     216                 :            :  */
     217                 :            : #define __verify_pcpu_ptr(ptr)                                          \
     218                 :            : do {                                                                    \
     219                 :            :         const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL;    \
     220                 :            :         (void)__vpp_verify;                                             \
     221                 :            : } while (0)
     222                 :            : 
     223                 :            : #ifdef CONFIG_SMP
     224                 :            : 
     225                 :            : /*
     226                 :            :  * Add an offset to a pointer but keep the pointer as-is.  Use RELOC_HIDE()
     227                 :            :  * to prevent the compiler from making incorrect assumptions about the
     228                 :            :  * pointer value.  The weird cast keeps both GCC and sparse happy.
     229                 :            :  */
     230                 :            : #define SHIFT_PERCPU_PTR(__p, __offset)                                 \
     231                 :            :         RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset))
     232                 :            : 
     233                 :            : #define per_cpu_ptr(ptr, cpu)                                           \
     234                 :            : ({                                                                      \
     235                 :            :         __verify_pcpu_ptr(ptr);                                         \
     236                 :            :         SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)));                 \
     237                 :            : })
     238                 :            : 
     239                 :            : #define raw_cpu_ptr(ptr)                                                \
     240                 :            : ({                                                                      \
     241                 :            :         __verify_pcpu_ptr(ptr);                                         \
     242                 :            :         arch_raw_cpu_ptr(ptr);                                          \
     243                 :            : })
     244                 :            : 
     245                 :            : #ifdef CONFIG_DEBUG_PREEMPT
     246                 :            : #define this_cpu_ptr(ptr)                                               \
     247                 :            : ({                                                                      \
     248                 :            :         __verify_pcpu_ptr(ptr);                                         \
     249                 :            :         SHIFT_PERCPU_PTR(ptr, my_cpu_offset);                           \
     250                 :            : })
     251                 :            : #else
     252                 :            : #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
     253                 :            : #endif
     254                 :            : 
     255                 :            : #else   /* CONFIG_SMP */
     256                 :            : 
     257                 :            : #define VERIFY_PERCPU_PTR(__p)                                          \
     258                 :            : ({                                                                      \
     259                 :            :         __verify_pcpu_ptr(__p);                                         \
     260                 :            :         (typeof(*(__p)) __kernel __force *)(__p);                       \
     261                 :            : })
     262                 :            : 
     263                 :            : #define per_cpu_ptr(ptr, cpu)   ({ (void)(cpu); VERIFY_PERCPU_PTR(ptr); })
     264                 :            : #define raw_cpu_ptr(ptr)        per_cpu_ptr(ptr, 0)
     265                 :            : #define this_cpu_ptr(ptr)       raw_cpu_ptr(ptr)
     266                 :            : 
     267                 :            : #endif  /* CONFIG_SMP */
     268                 :            : 
     269                 :            : #define per_cpu(var, cpu)       (*per_cpu_ptr(&(var), cpu))
     270                 :            : 
     271                 :            : /*
     272                 :            :  * Must be an lvalue. Since @var must be a simple identifier,
     273                 :            :  * we force a syntax error here if it isn't.
     274                 :            :  */
     275                 :            : #define get_cpu_var(var)                                                \
     276                 :            : (*({                                                                    \
     277                 :            :         preempt_disable();                                              \
     278                 :            :         this_cpu_ptr(&var);                                         \
     279                 :            : }))
     280                 :            : 
     281                 :            : /*
     282                 :            :  * The weird & is necessary because sparse considers (void)(var) to be
     283                 :            :  * a direct dereference of percpu variable (var).
     284                 :            :  */
     285                 :            : #define put_cpu_var(var)                                                \
     286                 :            : do {                                                                    \
     287                 :            :         (void)&(var);                                                       \
     288                 :            :         preempt_enable();                                               \
     289                 :            : } while (0)
     290                 :            : 
     291                 :            : #define get_cpu_ptr(var)                                                \
     292                 :            : ({                                                                      \
     293                 :            :         preempt_disable();                                              \
     294                 :            :         this_cpu_ptr(var);                                              \
     295                 :            : })
     296                 :            : 
     297                 :            : #define put_cpu_ptr(var)                                                \
     298                 :            : do {                                                                    \
     299                 :            :         (void)(var);                                                    \
     300                 :            :         preempt_enable();                                               \
     301                 :            : } while (0)
     302                 :            : 
     303                 :            : /*
     304                 :            :  * Branching function to split up a function into a set of functions that
     305                 :            :  * are called for different scalar sizes of the objects handled.
     306                 :            :  */
     307                 :            : 
     308                 :            : extern void __bad_size_call_parameter(void);
     309                 :            : 
     310                 :            : #ifdef CONFIG_DEBUG_PREEMPT
     311                 :            : extern void __this_cpu_preempt_check(const char *op);
     312                 :            : #else
     313   [ +  +  +  +  :  567285358 : static inline void __this_cpu_preempt_check(const char *op) { }
          +  +  +  +  +  
          +  +  +  +  +  
          +  +  +  +  +  
          +  +  +  -  -  
          -  -  -  -  -  
             -  -  -  -  
                      - ]
     314                 :            : #endif
     315                 :            : 
     316                 :            : #define __pcpu_size_call_return(stem, variable)                         \
     317                 :            : ({                                                                      \
     318                 :            :         typeof(variable) pscr_ret__;                                    \
     319                 :            :         __verify_pcpu_ptr(&(variable));                                     \
     320                 :            :         switch(sizeof(variable)) {                                      \
     321                 :            :         case 1: pscr_ret__ = stem##1(variable); break;                  \
     322                 :            :         case 2: pscr_ret__ = stem##2(variable); break;                  \
     323                 :            :         case 4: pscr_ret__ = stem##4(variable); break;                  \
     324                 :            :         case 8: pscr_ret__ = stem##8(variable); break;                  \
     325                 :            :         default:                                                        \
     326                 :            :                 __bad_size_call_parameter(); break;                     \
     327                 :            :         }                                                               \
     328                 :            :         pscr_ret__;                                                     \
     329                 :            : })
     330                 :            : 
     331                 :            : #define __pcpu_size_call_return2(stem, variable, ...)                   \
     332                 :            : ({                                                                      \
     333                 :            :         typeof(variable) pscr2_ret__;                                   \
     334                 :            :         __verify_pcpu_ptr(&(variable));                                     \
     335                 :            :         switch(sizeof(variable)) {                                      \
     336                 :            :         case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break;    \
     337                 :            :         case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break;    \
     338                 :            :         case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break;    \
     339                 :            :         case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break;    \
     340                 :            :         default:                                                        \
     341                 :            :                 __bad_size_call_parameter(); break;                     \
     342                 :            :         }                                                               \
     343                 :            :         pscr2_ret__;                                                    \
     344                 :            : })
     345                 :            : 
     346                 :            : /*
     347                 :            :  * Special handling for cmpxchg_double.  cmpxchg_double is passed two
     348                 :            :  * percpu variables.  The first has to be aligned to a double word
     349                 :            :  * boundary and the second has to follow directly thereafter.
     350                 :            :  * We enforce this on all architectures even if they don't support
     351                 :            :  * a double cmpxchg instruction, since it's a cheap requirement, and it
     352                 :            :  * avoids breaking the requirement for architectures with the instruction.
     353                 :            :  */
     354                 :            : #define __pcpu_double_call_return_bool(stem, pcp1, pcp2, ...)           \
     355                 :            : ({                                                                      \
     356                 :            :         bool pdcrb_ret__;                                               \
     357                 :            :         __verify_pcpu_ptr(&(pcp1));                                 \
     358                 :            :         BUILD_BUG_ON(sizeof(pcp1) != sizeof(pcp2));                     \
     359                 :            :         VM_BUG_ON((unsigned long)(&(pcp1)) % (2 * sizeof(pcp1)));   \
     360                 :            :         VM_BUG_ON((unsigned long)(&(pcp2)) !=                               \
     361                 :            :                   (unsigned long)(&(pcp1)) + sizeof(pcp1));         \
     362                 :            :         switch(sizeof(pcp1)) {                                          \
     363                 :            :         case 1: pdcrb_ret__ = stem##1(pcp1, pcp2, __VA_ARGS__); break;  \
     364                 :            :         case 2: pdcrb_ret__ = stem##2(pcp1, pcp2, __VA_ARGS__); break;  \
     365                 :            :         case 4: pdcrb_ret__ = stem##4(pcp1, pcp2, __VA_ARGS__); break;  \
     366                 :            :         case 8: pdcrb_ret__ = stem##8(pcp1, pcp2, __VA_ARGS__); break;  \
     367                 :            :         default:                                                        \
     368                 :            :                 __bad_size_call_parameter(); break;                     \
     369                 :            :         }                                                               \
     370                 :            :         pdcrb_ret__;                                                    \
     371                 :            : })
     372                 :            : 
     373                 :            : #define __pcpu_size_call(stem, variable, ...)                           \
     374                 :            : do {                                                                    \
     375                 :            :         __verify_pcpu_ptr(&(variable));                                     \
     376                 :            :         switch(sizeof(variable)) {                                      \
     377                 :            :                 case 1: stem##1(variable, __VA_ARGS__);break;           \
     378                 :            :                 case 2: stem##2(variable, __VA_ARGS__);break;           \
     379                 :            :                 case 4: stem##4(variable, __VA_ARGS__);break;           \
     380                 :            :                 case 8: stem##8(variable, __VA_ARGS__);break;           \
     381                 :            :                 default:                                                \
     382                 :            :                         __bad_size_call_parameter();break;              \
     383                 :            :         }                                                               \
     384                 :            : } while (0)
     385                 :            : 
     386                 :            : /*
     387                 :            :  * this_cpu operations (C) 2008-2013 Christoph Lameter <cl@linux.com>
     388                 :            :  *
     389                 :            :  * Optimized manipulation for memory allocated through the per cpu
     390                 :            :  * allocator or for addresses of per cpu variables.
     391                 :            :  *
     392                 :            :  * These operation guarantee exclusivity of access for other operations
     393                 :            :  * on the *same* processor. The assumption is that per cpu data is only
     394                 :            :  * accessed by a single processor instance (the current one).
     395                 :            :  *
     396                 :            :  * The arch code can provide optimized implementation by defining macros
     397                 :            :  * for certain scalar sizes. F.e. provide this_cpu_add_2() to provide per
     398                 :            :  * cpu atomic operations for 2 byte sized RMW actions. If arch code does
     399                 :            :  * not provide operations for a scalar size then the fallback in the
     400                 :            :  * generic code will be used.
     401                 :            :  *
     402                 :            :  * cmpxchg_double replaces two adjacent scalars at once.  The first two
     403                 :            :  * parameters are per cpu variables which have to be of the same size.  A
     404                 :            :  * truth value is returned to indicate success or failure (since a double
     405                 :            :  * register result is difficult to handle).  There is very limited hardware
     406                 :            :  * support for these operations, so only certain sizes may work.
     407                 :            :  */
     408                 :            : 
     409                 :            : /*
     410                 :            :  * Operations for contexts where we do not want to do any checks for
     411                 :            :  * preemptions.  Unless strictly necessary, always use [__]this_cpu_*()
     412                 :            :  * instead.
     413                 :            :  *
     414                 :            :  * If there is no other protection through preempt disable and/or disabling
     415                 :            :  * interupts then one of these RMW operations can show unexpected behavior
     416                 :            :  * because the execution thread was rescheduled on another processor or an
     417                 :            :  * interrupt occurred and the same percpu variable was modified from the
     418                 :            :  * interrupt context.
     419                 :            :  */
     420                 :            : #define raw_cpu_read(pcp)               __pcpu_size_call_return(raw_cpu_read_, pcp)
     421                 :            : #define raw_cpu_write(pcp, val)         __pcpu_size_call(raw_cpu_write_, pcp, val)
     422                 :            : #define raw_cpu_add(pcp, val)           __pcpu_size_call(raw_cpu_add_, pcp, val)
     423                 :            : #define raw_cpu_and(pcp, val)           __pcpu_size_call(raw_cpu_and_, pcp, val)
     424                 :            : #define raw_cpu_or(pcp, val)            __pcpu_size_call(raw_cpu_or_, pcp, val)
     425                 :            : #define raw_cpu_add_return(pcp, val)    __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val)
     426                 :            : #define raw_cpu_xchg(pcp, nval)         __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval)
     427                 :            : #define raw_cpu_cmpxchg(pcp, oval, nval) \
     428                 :            :         __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
     429                 :            : #define raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
     430                 :            :         __pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
     431                 :            : 
     432                 :            : #define raw_cpu_sub(pcp, val)           raw_cpu_add(pcp, -(val))
     433                 :            : #define raw_cpu_inc(pcp)                raw_cpu_add(pcp, 1)
     434                 :            : #define raw_cpu_dec(pcp)                raw_cpu_sub(pcp, 1)
     435                 :            : #define raw_cpu_sub_return(pcp, val)    raw_cpu_add_return(pcp, -(typeof(pcp))(val))
     436                 :            : #define raw_cpu_inc_return(pcp)         raw_cpu_add_return(pcp, 1)
     437                 :            : #define raw_cpu_dec_return(pcp)         raw_cpu_add_return(pcp, -1)
     438                 :            : 
     439                 :            : /*
     440                 :            :  * Operations for contexts that are safe from preemption/interrupts.  These
     441                 :            :  * operations verify that preemption is disabled.
     442                 :            :  */
     443                 :            : #define __this_cpu_read(pcp)                                            \
     444                 :            : ({                                                                      \
     445                 :            :         __this_cpu_preempt_check("read");                             \
     446                 :            :         raw_cpu_read(pcp);                                              \
     447                 :            : })
     448                 :            : 
     449                 :            : #define __this_cpu_write(pcp, val)                                      \
     450                 :            : ({                                                                      \
     451                 :            :         __this_cpu_preempt_check("write");                            \
     452                 :            :         raw_cpu_write(pcp, val);                                        \
     453                 :            : })
     454                 :            : 
     455                 :            : #define __this_cpu_add(pcp, val)                                        \
     456                 :            : ({                                                                      \
     457                 :            :         __this_cpu_preempt_check("add");                              \
     458                 :            :         raw_cpu_add(pcp, val);                                          \
     459                 :            : })
     460                 :            : 
     461                 :            : #define __this_cpu_and(pcp, val)                                        \
     462                 :            : ({                                                                      \
     463                 :            :         __this_cpu_preempt_check("and");                              \
     464                 :            :         raw_cpu_and(pcp, val);                                          \
     465                 :            : })
     466                 :            : 
     467                 :            : #define __this_cpu_or(pcp, val)                                         \
     468                 :            : ({                                                                      \
     469                 :            :         __this_cpu_preempt_check("or");                                       \
     470                 :            :         raw_cpu_or(pcp, val);                                           \
     471                 :            : })
     472                 :            : 
     473                 :            : #define __this_cpu_add_return(pcp, val)                                 \
     474                 :            : ({                                                                      \
     475                 :            :         __this_cpu_preempt_check("add_return");                               \
     476                 :            :         raw_cpu_add_return(pcp, val);                                   \
     477                 :            : })
     478                 :            : 
     479                 :            : #define __this_cpu_xchg(pcp, nval)                                      \
     480                 :            : ({                                                                      \
     481                 :            :         __this_cpu_preempt_check("xchg");                             \
     482                 :            :         raw_cpu_xchg(pcp, nval);                                        \
     483                 :            : })
     484                 :            : 
     485                 :            : #define __this_cpu_cmpxchg(pcp, oval, nval)                             \
     486                 :            : ({                                                                      \
     487                 :            :         __this_cpu_preempt_check("cmpxchg");                          \
     488                 :            :         raw_cpu_cmpxchg(pcp, oval, nval);                               \
     489                 :            : })
     490                 :            : 
     491                 :            : #define __this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
     492                 :            : ({      __this_cpu_preempt_check("cmpxchg_double");                   \
     493                 :            :         raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2); \
     494                 :            : })
     495                 :            : 
     496                 :            : #define __this_cpu_sub(pcp, val)        __this_cpu_add(pcp, -(typeof(pcp))(val))
     497                 :            : #define __this_cpu_inc(pcp)             __this_cpu_add(pcp, 1)
     498                 :            : #define __this_cpu_dec(pcp)             __this_cpu_sub(pcp, 1)
     499                 :            : #define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val))
     500                 :            : #define __this_cpu_inc_return(pcp)      __this_cpu_add_return(pcp, 1)
     501                 :            : #define __this_cpu_dec_return(pcp)      __this_cpu_add_return(pcp, -1)
     502                 :            : 
     503                 :            : /*
     504                 :            :  * Operations with implied preemption/interrupt protection.  These
     505                 :            :  * operations can be used without worrying about preemption or interrupt.
     506                 :            :  */
     507                 :            : #define this_cpu_read(pcp)              __pcpu_size_call_return(this_cpu_read_, pcp)
     508                 :            : #define this_cpu_write(pcp, val)        __pcpu_size_call(this_cpu_write_, pcp, val)
     509                 :            : #define this_cpu_add(pcp, val)          __pcpu_size_call(this_cpu_add_, pcp, val)
     510                 :            : #define this_cpu_and(pcp, val)          __pcpu_size_call(this_cpu_and_, pcp, val)
     511                 :            : #define this_cpu_or(pcp, val)           __pcpu_size_call(this_cpu_or_, pcp, val)
     512                 :            : #define this_cpu_add_return(pcp, val)   __pcpu_size_call_return2(this_cpu_add_return_, pcp, val)
     513                 :            : #define this_cpu_xchg(pcp, nval)        __pcpu_size_call_return2(this_cpu_xchg_, pcp, nval)
     514                 :            : #define this_cpu_cmpxchg(pcp, oval, nval) \
     515                 :            :         __pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval)
     516                 :            : #define this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
     517                 :            :         __pcpu_double_call_return_bool(this_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
     518                 :            : 
     519                 :            : #define this_cpu_sub(pcp, val)          this_cpu_add(pcp, -(typeof(pcp))(val))
     520                 :            : #define this_cpu_inc(pcp)               this_cpu_add(pcp, 1)
     521                 :            : #define this_cpu_dec(pcp)               this_cpu_sub(pcp, 1)
     522                 :            : #define this_cpu_sub_return(pcp, val)   this_cpu_add_return(pcp, -(typeof(pcp))(val))
     523                 :            : #define this_cpu_inc_return(pcp)        this_cpu_add_return(pcp, 1)
     524                 :            : #define this_cpu_dec_return(pcp)        this_cpu_add_return(pcp, -1)
     525                 :            : 
     526                 :            : #endif /* __ASSEMBLY__ */
     527                 :            : #endif /* _LINUX_PERCPU_DEFS_H */

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