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 #define notrace __attribute__((no_instrument_function))
  48
  49 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  50  * coming from above header files here
  51  */
  52 #ifdef __INTEL_COMPILER
  53 # include <linux/compiler-intel.h>
  54 #endif
  55
  56 /*
  57  * Generic compiler-dependent macros required for kernel
  58  * build go below this comment. Actual compiler/compiler version
  59  * specific implementations come from the above header files
  60  */
  61
  62 #define likely(x)       __builtin_expect(!!(x), 1)
  63 #define unlikely(x)     __builtin_expect(!!(x), 0)
  64
  65 /* Optimization barrier */
  66 #ifndef barrier
  67 # define barrier() __memory_barrier()
  68 #endif
  69
  70 #ifndef RELOC_HIDE
  71 # define RELOC_HIDE(ptr, off)                                   \
  72   ({ unsigned long __ptr;                                       \
  73      __ptr = (unsigned long) (ptr);                             \
  74     (typeof(ptr)) (__ptr + (off)); })
  75 #endif
  76
  77 #endif /* __KERNEL__ */
  78
  79 #endif /* __ASSEMBLY__ */
  80
  81 #ifdef __KERNEL__
  82 /*
  83  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
  84  * warning for each use, in hopes of speeding the functions removal.
  85  * Usage is:
  86  *              int __deprecated foo(void)
  87  */
  88 #ifndef __deprecated
  89 # define __deprecated           /* unimplemented */
  90 #endif
  91
  92 #ifdef MODULE
  93 #define __deprecated_for_modules __deprecated
  94 #else
  95 #define __deprecated_for_modules
  96 #endif
  97
  98 #ifndef __must_check
  99 #define __must_check
 100 #endif
 101
 102 #ifndef CONFIG_ENABLE_MUST_CHECK
 103 #undef __must_check
 104 #define __must_check
 105 #endif
 106 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
 107 #undef __deprecated
 108 #undef __deprecated_for_modules
 109 #define __deprecated
 110 #define __deprecated_for_modules
 111 #endif
 112
 113 /*
 114  * Allow us to avoid 'defined but not used' warnings on functions and data,
 115  * as well as force them to be emitted to the assembly file.
 116  *
 117  * As of gcc 3.4, static functions that are not marked with attribute((used))
 118  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 119  * marked will not be elided, but this may change in a future gcc version.
 120  *
 121  * NOTE: Because distributions shipped with a backported unit-at-a-time
 122  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 123  * for gcc >=3.3 instead of 3.4.
 124  *
 125  * In prior versions of gcc, such functions and data would be emitted, but
 126  * would be warned about except with attribute((unused)).
 127  *
 128  * Mark functions that are referenced only in inline assembly as __used so
 129  * the code is emitted even though it appears to be unreferenced.
 130  */
 131 #ifndef __used
 132 # define __used                 /* unimplemented */
 133 #endif
 134
 135 #ifndef __maybe_unused
 136 # define __maybe_unused         /* unimplemented */
 137 #endif
 138
 139 #ifndef noinline
 140 #define noinline
 141 #endif
 142
 143 /*
 144  * Rather then using noinline to prevent stack consumption, use
 145  * noinline_for_stack instead.  For documentaiton reasons.
 146  */
 147 #define noinline_for_stack noinline
 148
 149 #ifndef __always_inline
 150 #define __always_inline inline
 151 #endif
 152
 153 #endif /* __KERNEL__ */
 154
 155 /*
 156  * From the GCC manual:
 157  *
 158  * Many functions do not examine any values except their arguments,
 159  * and have no effects except the return value.  Basically this is
 160  * just slightly more strict class than the `pure' attribute above,
 161  * since function is not allowed to read global memory.
 162  *
 163  * Note that a function that has pointer arguments and examines the
 164  * data pointed to must _not_ be declared `const'.  Likewise, a
 165  * function that calls a non-`const' function usually must not be
 166  * `const'.  It does not make sense for a `const' function to return
 167  * `void'.
 168  */
 169 #ifndef __attribute_const__
 170 # define __attribute_const__    /* unimplemented */
 171 #endif
 172
 173 /*
 174  * Tell gcc if a function is cold. The compiler will assume any path
 175  * directly leading to the call is unlikely.
 176  */
 177
 178 #ifndef __cold
 179 #define __cold
 180 #endif
 181
 182 /* Simple shorthand for a section definition */
 183 #ifndef __section
 184 # define __section(S) __attribute__ ((__section__(#S)))
 185 #endif
 186
 187 /*
 188  * Prevent the compiler from merging or refetching accesses.  The compiler
 189  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 190  * but only when the compiler is aware of some particular ordering.  One way
 191  * to make the compiler aware of ordering is to put the two invocations of
 192  * ACCESS_ONCE() in different C statements.
 193  *
 194  * This macro does absolutely -nothing- to prevent the CPU from reordering,
 195  * merging, or refetching absolutely anything at any time.  Its main intended
 196  * use is to mediate communication between process-level code and irq/NMI
 197  * handlers, all running on the same CPU.
 198  */
 199 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 200
 201 #endif /* __LINUX_COMPILER_H */