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 struct ftrace_branch_data {
  63         const char *func;
  64         const char *file;
  65         unsigned line;
  66         union {
  67                 struct {
  68                         unsigned long correct;
  69                         unsigned long incorrect;
  70                 };
  71                 struct {
  72                         unsigned long miss;
  73                         unsigned long hit;
  74                 };
  75         };
  76 };
  77
  78 /*
  79  * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
  80  * to disable branch tracing on a per file basis.
  81  */
  82 #if defined(CONFIG_TRACE_BRANCH_PROFILING) && !defined(DISABLE_BRANCH_PROFILING)
  83 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
  84
  85 #define likely_notrace(x)       __builtin_expect(!!(x), 1)
  86 #define unlikely_notrace(x)     __builtin_expect(!!(x), 0)
  87
  88 #define __branch_check__(x, expect) ({                                  \
  89                         int ______r;                                    \
  90                         static struct ftrace_branch_data                \
  91                                 __attribute__((__aligned__(4)))         \
  92                                 __attribute__((section("_ftrace_annotated_branch"))) \
  93                                 ______f = {                             \
  94                                 .func = __func__,                       \
  95                                 .file = __FILE__,                       \
  96                                 .line = __LINE__,                       \
  97                         };                                              \
  98                         ______r = likely_notrace(x);                    \
  99                         ftrace_likely_update(&______f, ______r, expect); \
 100                         ______r;                                        \
 101                 })
 102
 103 /*
 104  * Using __builtin_constant_p(x) to ignore cases where the return
 105  * value is always the same.  This idea is taken from a similar patch
 106  * written by Daniel Walker.
 107  */
 108 # ifndef likely
 109 #  define likely(x)     (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
 110 # endif
 111 # ifndef unlikely
 112 #  define unlikely(x)   (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
 113 # endif
 114
 115 #ifdef CONFIG_PROFILE_ALL_BRANCHES
 116 /*
 117  * "Define 'is'", Bill Clinton
 118  * "Define 'if'", Steven Rostedt
 119  */
 120 #define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) :          \
 121         ({                                                              \
 122                 int ______r;                                            \
 123                 static struct ftrace_branch_data                        \
 124                         __attribute__((__aligned__(4)))                 \
 125                         __attribute__((section("_ftrace_branch")))      \
 126                         ______f = {                                     \
 127                                 .func = __func__,                       \
 128                                 .file = __FILE__,                       \
 129                                 .line = __LINE__,                       \
 130                         };                                              \
 131                 ______r = !!(cond);                                     \
 132                 if (______r)                                            \
 133                         ______f.hit++;                                  \
 134                 else                                                    \
 135                         ______f.miss++;                                 \
 136                 ______r;                                                \
 137         }))
 138 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
 139
 140 #else
 141 # define likely(x)      __builtin_expect(!!(x), 1)
 142 # define unlikely(x)    __builtin_expect(!!(x), 0)
 143 #endif
 144
 145 /* Optimization barrier */
 146 #ifndef barrier
 147 # define barrier() __memory_barrier()
 148 #endif
 149
 150 #ifndef RELOC_HIDE
 151 # define RELOC_HIDE(ptr, off)                                   \
 152   ({ unsigned long __ptr;                                       \
 153      __ptr = (unsigned long) (ptr);                             \
 154     (typeof(ptr)) (__ptr + (off)); })
 155 #endif
 156
 157 #endif /* __KERNEL__ */
 158
 159 #endif /* __ASSEMBLY__ */
 160
 161 #ifdef __KERNEL__
 162 /*
 163  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 164  * warning for each use, in hopes of speeding the functions removal.
 165  * Usage is:
 166  *              int __deprecated foo(void)
 167  */
 168 #ifndef __deprecated
 169 # define __deprecated           /* unimplemented */
 170 #endif
 171
 172 #ifdef MODULE
 173 #define __deprecated_for_modules __deprecated
 174 #else
 175 #define __deprecated_for_modules
 176 #endif
 177
 178 #ifndef __must_check
 179 #define __must_check
 180 #endif
 181
 182 #ifndef CONFIG_ENABLE_MUST_CHECK
 183 #undef __must_check
 184 #define __must_check
 185 #endif
 186 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
 187 #undef __deprecated
 188 #undef __deprecated_for_modules
 189 #define __deprecated
 190 #define __deprecated_for_modules
 191 #endif
 192
 193 /*
 194  * Allow us to avoid 'defined but not used' warnings on functions and data,
 195  * as well as force them to be emitted to the assembly file.
 196  *
 197  * As of gcc 3.4, static functions that are not marked with attribute((used))
 198  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 199  * marked will not be elided, but this may change in a future gcc version.
 200  *
 201  * NOTE: Because distributions shipped with a backported unit-at-a-time
 202  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 203  * for gcc >=3.3 instead of 3.4.
 204  *
 205  * In prior versions of gcc, such functions and data would be emitted, but
 206  * would be warned about except with attribute((unused)).
 207  *
 208  * Mark functions that are referenced only in inline assembly as __used so
 209  * the code is emitted even though it appears to be unreferenced.
 210  */
 211 #ifndef __used
 212 # define __used                 /* unimplemented */
 213 #endif
 214
 215 #ifndef __maybe_unused
 216 # define __maybe_unused         /* unimplemented */
 217 #endif
 218
 219 #ifndef noinline
 220 #define noinline
 221 #endif
 222
 223 /*
 224  * Rather then using noinline to prevent stack consumption, use
 225  * noinline_for_stack instead.  For documentaiton reasons.
 226  */
 227 #define noinline_for_stack noinline
 228
 229 #ifndef __always_inline
 230 #define __always_inline inline
 231 #endif
 232
 233 #endif /* __KERNEL__ */
 234
 235 /*
 236  * From the GCC manual:
 237  *
 238  * Many functions do not examine any values except their arguments,
 239  * and have no effects except the return value.  Basically this is
 240  * just slightly more strict class than the `pure' attribute above,
 241  * since function is not allowed to read global memory.
 242  *
 243  * Note that a function that has pointer arguments and examines the
 244  * data pointed to must _not_ be declared `const'.  Likewise, a
 245  * function that calls a non-`const' function usually must not be
 246  * `const'.  It does not make sense for a `const' function to return
 247  * `void'.
 248  */
 249 #ifndef __attribute_const__
 250 # define __attribute_const__    /* unimplemented */
 251 #endif
 252
 253 /*
 254  * Tell gcc if a function is cold. The compiler will assume any path
 255  * directly leading to the call is unlikely.
 256  */
 257
 258 #ifndef __cold
 259 #define __cold
 260 #endif
 261
 262 /* Simple shorthand for a section definition */
 263 #ifndef __section
 264 # define __section(S) __attribute__ ((__section__(#S)))
 265 #endif
 266
 267 /*
 268  * Prevent the compiler from merging or refetching accesses.  The compiler
 269  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 270  * but only when the compiler is aware of some particular ordering.  One way
 271  * to make the compiler aware of ordering is to put the two invocations of
 272  * ACCESS_ONCE() in different C statements.
 273  *
 274  * This macro does absolutely -nothing- to prevent the CPU from reordering,
 275  * merging, or refetching absolutely anything at any time.  Its main intended
 276  * use is to mediate communication between process-level code and irq/NMI
 277  * handlers, all running on the same CPU.
 278  */
 279 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 280
 281 #endif /* __LINUX_COMPILER_H */