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       __attribute__((address_space(0)))
   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 # define __percpu       __attribute__((noderef, address_space(3)))
  19 #ifdef CONFIG_SPARSE_RCU_POINTER
  20 # define __rcu          __attribute__((noderef, address_space(4)))
  21 #else
  22 # define __rcu
  23 #endif
  24 extern void __chk_user_ptr(const volatile void __user *);
  25 extern void __chk_io_ptr(const volatile void __iomem *);
  26 #else
  27 # define __user
  28 # define __kernel
  29 # define __safe
  30 # define __force
  31 # define __nocast
  32 # define __iomem
  33 # define __chk_user_ptr(x) (void)0
  34 # define __chk_io_ptr(x) (void)0
  35 # define __builtin_warning(x, y...) (1)
  36 # define __acquires(x)
  37 # define __releases(x)
  38 # define __acquire(x) (void)0
  39 # define __release(x) (void)0
  40 # define __cond_lock(x,c) (c)
  41 # define __percpu
  42 # define __rcu
  43 #endif
  44
  45 #ifdef __KERNEL__
  46
  47 #ifdef __GNUC__
  48 #include <linux/compiler-gcc.h>
  49 #endif
  50
  51 #define notrace __attribute__((no_instrument_function))
  52
  53 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  54  * coming from above header files here
  55  */
  56 #ifdef __INTEL_COMPILER
  57 # include <linux/compiler-intel.h>
  58 #endif
  59
  60 /*
  61  * Generic compiler-dependent macros required for kernel
  62  * build go below this comment. Actual compiler/compiler version
  63  * specific implementations come from the above header files
  64  */
  65
  66 struct ftrace_branch_data {
  67         const char *func;
  68         const char *file;
  69         unsigned line;
  70         union {
  71                 struct {
  72                         unsigned long correct;
  73                         unsigned long incorrect;
  74                 };
  75                 struct {
  76                         unsigned long miss;
  77                         unsigned long hit;
  78                 };
  79                 unsigned long miss_hit[2];
  80         };
  81 };
  82
  83 /*
  84  * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
  85  * to disable branch tracing on a per file basis.
  86  */
  87 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
  88     && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
  89 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
  90
  91 #define likely_notrace(x)       __builtin_expect(!!(x), 1)
  92 #define unlikely_notrace(x)     __builtin_expect(!!(x), 0)
  93
  94 #define __branch_check__(x, expect) ({                                  \
  95                         int ______r;                                    \
  96                         static struct ftrace_branch_data                \
  97                                 __attribute__((__aligned__(4)))         \
  98                                 __attribute__((section("_ftrace_annotated_branch"))) \
  99                                 ______f = {                             \
 100                                 .func = __func__,                       \
 101                                 .file = __FILE__,                       \
 102                                 .line = __LINE__,                       \
 103                         };                                              \
 104                         ______r = likely_notrace(x);                    \
 105                         ftrace_likely_update(&______f, ______r, expect); \
 106                         ______r;                                        \
 107                 })
 108
 109 /*
 110  * Using __builtin_constant_p(x) to ignore cases where the return
 111  * value is always the same.  This idea is taken from a similar patch
 112  * written by Daniel Walker.
 113  */
 114 # ifndef likely
 115 #  define likely(x)     (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
 116 # endif
 117 # ifndef unlikely
 118 #  define unlikely(x)   (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
 119 # endif
 120
 121 #ifdef CONFIG_PROFILE_ALL_BRANCHES
 122 /*
 123  * "Define 'is'", Bill Clinton
 124  * "Define 'if'", Steven Rostedt
 125  */
 126 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
 127 #define __trace_if(cond) \
 128         if (__builtin_constant_p((cond)) ? !!(cond) :                   \
 129         ({                                                              \
 130                 int ______r;                                            \
 131                 static struct ftrace_branch_data                        \
 132                         __attribute__((__aligned__(4)))                 \
 133                         __attribute__((section("_ftrace_branch")))      \
 134                         ______f = {                                     \
 135                                 .func = __func__,                       \
 136                                 .file = __FILE__,                       \
 137                                 .line = __LINE__,                       \
 138                         };                                              \
 139                 ______r = !!(cond);                                     \
 140                 ______f.miss_hit[______r]++;                                    \
 141                 ______r;                                                \
 142         }))
 143 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
 144
 145 #else
 146 # define likely(x)      __builtin_expect(!!(x), 1)
 147 # define unlikely(x)    __builtin_expect(!!(x), 0)
 148 #endif
 149
 150 /* Optimization barrier */
 151 #ifndef barrier
 152 # define barrier() __memory_barrier()
 153 #endif
 154
 155 /* Unreachable code */
 156 #ifndef unreachable
 157 # define unreachable() do { } while (1)
 158 #endif
 159
 160 #ifndef RELOC_HIDE
 161 # define RELOC_HIDE(ptr, off)                                   \
 162   ({ unsigned long __ptr;                                       \
 163      __ptr = (unsigned long) (ptr);                             \
 164     (typeof(ptr)) (__ptr + (off)); })
 165 #endif
 166
 167 #endif /* __KERNEL__ */
 168
 169 #endif /* __ASSEMBLY__ */
 170
 171 #ifdef __KERNEL__
 172 /*
 173  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 174  * warning for each use, in hopes of speeding the functions removal.
 175  * Usage is:
 176  *              int __deprecated foo(void)
 177  */
 178 #ifndef __deprecated
 179 # define __deprecated           /* unimplemented */
 180 #endif
 181
 182 #ifdef MODULE
 183 #define __deprecated_for_modules __deprecated
 184 #else
 185 #define __deprecated_for_modules
 186 #endif
 187
 188 #ifndef __must_check
 189 #define __must_check
 190 #endif
 191
 192 #ifndef CONFIG_ENABLE_MUST_CHECK
 193 #undef __must_check
 194 #define __must_check
 195 #endif
 196 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
 197 #undef __deprecated
 198 #undef __deprecated_for_modules
 199 #define __deprecated
 200 #define __deprecated_for_modules
 201 #endif
 202
 203 /*
 204  * Allow us to avoid 'defined but not used' warnings on functions and data,
 205  * as well as force them to be emitted to the assembly file.
 206  *
 207  * As of gcc 3.4, static functions that are not marked with attribute((used))
 208  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 209  * marked will not be elided, but this may change in a future gcc version.
 210  *
 211  * NOTE: Because distributions shipped with a backported unit-at-a-time
 212  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 213  * for gcc >=3.3 instead of 3.4.
 214  *
 215  * In prior versions of gcc, such functions and data would be emitted, but
 216  * would be warned about except with attribute((unused)).
 217  *
 218  * Mark functions that are referenced only in inline assembly as __used so
 219  * the code is emitted even though it appears to be unreferenced.
 220  */
 221 #ifndef __used
 222 # define __used                 /* unimplemented */
 223 #endif
 224
 225 #ifndef __maybe_unused
 226 # define __maybe_unused         /* unimplemented */
 227 #endif
 228
 229 #ifndef __always_unused
 230 # define __always_unused        /* unimplemented */
 231 #endif
 232
 233 #ifndef noinline
 234 #define noinline
 235 #endif
 236
 237 /*
 238  * Rather then using noinline to prevent stack consumption, use
 239  * noinline_for_stack instead.  For documentation reasons.
 240  */
 241 #define noinline_for_stack noinline
 242
 243 #ifndef __always_inline
 244 #define __always_inline inline
 245 #endif
 246
 247 #endif /* __KERNEL__ */
 248
 249 /*
 250  * From the GCC manual:
 251  *
 252  * Many functions do not examine any values except their arguments,
 253  * and have no effects except the return value.  Basically this is
 254  * just slightly more strict class than the `pure' attribute above,
 255  * since function is not allowed to read global memory.
 256  *
 257  * Note that a function that has pointer arguments and examines the
 258  * data pointed to must _not_ be declared `const'.  Likewise, a
 259  * function that calls a non-`const' function usually must not be
 260  * `const'.  It does not make sense for a `const' function to return
 261  * `void'.
 262  */
 263 #ifndef __attribute_const__
 264 # define __attribute_const__    /* unimplemented */
 265 #endif
 266
 267 /*
 268  * Tell gcc if a function is cold. The compiler will assume any path
 269  * directly leading to the call is unlikely.
 270  */
 271
 272 #ifndef __cold
 273 #define __cold
 274 #endif
 275
 276 /* Simple shorthand for a section definition */
 277 #ifndef __section
 278 # define __section(S) __attribute__ ((__section__(#S)))
 279 #endif
 280
 281 #ifndef __visible
 282 #define __visible
 283 #endif
 284
 285 /* Are two types/vars the same type (ignoring qualifiers)? */
 286 #ifndef __same_type
 287 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
 288 #endif
 289
 290 /* Compile time object size, -1 for unknown */
 291 #ifndef __compiletime_object_size
 292 # define __compiletime_object_size(obj) -1
 293 #endif
 294 #ifndef __compiletime_warning
 295 # define __compiletime_warning(message)
 296 #endif
 297 #ifndef __compiletime_error
 298 # define __compiletime_error(message)
 299 #endif
 300 #ifndef __linktime_error
 301 # define __linktime_error(message)
 302 #endif
 303 /*
 304  * Prevent the compiler from merging or refetching accesses.  The compiler
 305  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 306  * but only when the compiler is aware of some particular ordering.  One way
 307  * to make the compiler aware of ordering is to put the two invocations of
 308  * ACCESS_ONCE() in different C statements.
 309  *
 310  * This macro does absolutely -nothing- to prevent the CPU from reordering,
 311  * merging, or refetching absolutely anything at any time.  Its main intended
 312  * use is to mediate communication between process-level code and irq/NMI
 313  * handlers, all running on the same CPU.
 314  */
 315 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 316
 317 #endif /* __LINUX_COMPILER_H */