include/linux/compiler.h

   1 #ifndef __LINUX_COMPILER_H
   2 #define __LINUX_COMPILER_H
   3
   4 #ifndef __ASSEMBLY__
   5
   6 #ifdef __CHECKER__
   7 # define __user         __attribute__((noderef, address_space(1)))
   8 # define __kernel       /* default address space */
   9 # define __safe         __attribute__((safe))
  10 # define __force        __attribute__((force))
  11 # define __nocast       __attribute__((nocast))
  12 # define __iomem        __attribute__((noderef, address_space(2)))
  13 # define __acquires(x)  __attribute__((context(x,0,1)))
  14 # define __releases(x)  __attribute__((context(x,1,0)))
  15 # define __acquire(x)   __context__(x,1)
  16 # define __release(x)   __context__(x,-1)
  17 # define __cond_lock(x,c)       ((c) ? ({ __acquire(x); 1; }) : 0)
  18 extern void __chk_user_ptr(const volatile void __user *);
  19 extern void __chk_io_ptr(const volatile void __iomem *);
  20 #else
  21 # define __user
  22 # define __kernel
  23 # define __safe
  24 # define __force
  25 # define __nocast
  26 # define __iomem
  27 # define __chk_user_ptr(x) (void)0
  28 # define __chk_io_ptr(x) (void)0
  29 # define __builtin_warning(x, y...) (1)
  30 # define __acquires(x)
  31 # define __releases(x)
  32 # define __acquire(x) (void)0
  33 # define __release(x) (void)0
  34 # define __cond_lock(x,c) (c)
  35 #endif
  36
  37 #ifdef __KERNEL__
  38
  39 #if __GNUC__ >= 4
  40 # include <linux/compiler-gcc4.h>
  41 #elif __GNUC__ == 3 && __GNUC_MINOR__ >= 2
  42 # include <linux/compiler-gcc3.h>
  43 #else
  44 # error Sorry, your compiler is too old/not recognized.
  45 #endif
  46
  47 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  48  * coming from above header files here
  49  */
  50 #ifdef __INTEL_COMPILER
  51 # include <linux/compiler-intel.h>
  52 #endif
  53
  54 /*
  55  * Generic compiler-dependent macros required for kernel
  56  * build go below this comment. Actual compiler/compiler version
  57  * specific implementations come from the above header files
  58  */
  59
  60 #define likely(x)       __builtin_expect(!!(x), 1)
  61 #define unlikely(x)     __builtin_expect(!!(x), 0)
  62
  63 /* Optimization barrier */
  64 #ifndef barrier
  65 # define barrier() __memory_barrier()
  66 #endif
  67
  68 #ifndef RELOC_HIDE
  69 # define RELOC_HIDE(ptr, off)                                   \
  70   ({ unsigned long __ptr;                                       \
  71      __ptr = (unsigned long) (ptr);                             \
  72     (typeof(ptr)) (__ptr + (off)); })
  73 #endif
  74
  75 #endif /* __KERNEL__ */
  76
  77 #endif /* __ASSEMBLY__ */
  78
  79 #ifdef __KERNEL__
  80 /*
  81  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
  82  * warning for each use, in hopes of speeding the functions removal.
  83  * Usage is:
  84  *              int __deprecated foo(void)
  85  */
  86 #ifndef __deprecated
  87 # define __deprecated           /* unimplemented */
  88 #endif
  89
  90 #ifdef MODULE
  91 #define __deprecated_for_modules __deprecated
  92 #else
  93 #define __deprecated_for_modules
  94 #endif
  95
  96 #ifndef __must_check
  97 #define __must_check
  98 #endif
  99
 100 #ifndef CONFIG_ENABLE_MUST_CHECK
 101 #undef __must_check
 102 #define __must_check
 103 #endif
 104 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
 105 #undef __deprecated
 106 #undef __deprecated_for_modules
 107 #define __deprecated
 108 #define __deprecated_for_modules
 109 #endif
 110
 111 /*
 112  * Allow us to avoid 'defined but not used' warnings on functions and data,
 113  * as well as force them to be emitted to the assembly file.
 114  *
 115  * As of gcc 3.4, static functions that are not marked with attribute((used))
 116  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 117  * marked will not be elided, but this may change in a future gcc version.
 118  *
 119  * NOTE: Because distributions shipped with a backported unit-at-a-time
 120  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 121  * for gcc >=3.3 instead of 3.4.
 122  *
 123  * In prior versions of gcc, such functions and data would be emitted, but
 124  * would be warned about except with attribute((unused)).
 125  *
 126  * Mark functions that are referenced only in inline assembly as __used so
 127  * the code is emitted even though it appears to be unreferenced.
 128  */
 129 #ifndef __used
 130 # define __used                 /* unimplemented */
 131 #endif
 132
 133 #ifndef __maybe_unused
 134 # define __maybe_unused         /* unimplemented */
 135 #endif
 136
 137 #ifndef noinline
 138 #define noinline
 139 #endif
 140
 141 /*
 142  * Rather then using noinline to prevent stack consumption, use
 143  * noinline_for_stack instead.  For documentaiton reasons.
 144  */
 145 #define noinline_for_stack noinline
 146
 147 #ifndef __always_inline
 148 #define __always_inline inline
 149 #endif
 150
 151 #endif /* __KERNEL__ */
 152
 153 /*
 154  * From the GCC manual:
 155  *
 156  * Many functions do not examine any values except their arguments,
 157  * and have no effects except the return value.  Basically this is
 158  * just slightly more strict class than the `pure' attribute above,
 159  * since function is not allowed to read global memory.
 160  *
 161  * Note that a function that has pointer arguments and examines the
 162  * data pointed to must _not_ be declared `const'.  Likewise, a
 163  * function that calls a non-`const' function usually must not be
 164  * `const'.  It does not make sense for a `const' function to return
 165  * `void'.
 166  */
 167 #ifndef __attribute_const__
 168 # define __attribute_const__    /* unimplemented */
 169 #endif
 170
 171 /*
 172  * Tell gcc if a function is cold. The compiler will assume any path
 173  * directly leading to the call is unlikely.
 174  */
 175
 176 #ifndef __cold
 177 #define __cold
 178 #endif
 179
 180 /* Simple shorthand for a section definition */
 181 #ifndef __section
 182 # define __section(S) __attribute__ ((__section__(#S)))
 183 #endif
 184
 185 /*
 186  * Prevent the compiler from merging or refetching accesses.  The compiler
 187  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 188  * but only when the compiler is aware of some particular ordering.  One way
 189  * to make the compiler aware of ordering is to put the two invocations of
 190  * ACCESS_ONCE() in different C statements.
 191  *
 192  * This macro does absolutely -nothing- to prevent the CPU from reordering,
 193  * merging, or refetching absolutely anything at any time.
 194  */
 195 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 196
 197 #endif /* __LINUX_COMPILER_H */