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 __must_hold(x) __attribute__((context(x,1,1)))
  14 # define __acquires(x)  __attribute__((context(x,0,1)))
  15 # define __releases(x)  __attribute__((context(x,1,0)))
  16 # define __acquire(x)   __context__(x,1)
  17 # define __release(x)   __context__(x,-1)
  18 # define __cond_lock(x,c)       ((c) ? ({ __acquire(x); 1; }) : 0)
  19 # define __percpu       __attribute__((noderef, address_space(3)))
  20 #ifdef CONFIG_SPARSE_RCU_POINTER
  21 # define __rcu          __attribute__((noderef, address_space(4)))
  22 #else
  23 # define __rcu
  24 #endif
  25 extern void __chk_user_ptr(const volatile void __user *);
  26 extern void __chk_io_ptr(const volatile void __iomem *);
  27 #else
  28 # define __user
  29 # define __kernel
  30 # define __safe
  31 # define __force
  32 # define __nocast
  33 # define __iomem
  34 # define __chk_user_ptr(x) (void)0
  35 # define __chk_io_ptr(x) (void)0
  36 # define __builtin_warning(x, y...) (1)
  37 # define __must_hold(x)
  38 # define __acquires(x)
  39 # define __releases(x)
  40 # define __acquire(x) (void)0
  41 # define __release(x) (void)0
  42 # define __cond_lock(x,c) (c)
  43 # define __percpu
  44 # define __rcu
  45 #endif
  46
  47 #ifdef __KERNEL__
  48
  49 #ifdef __GNUC__
  50 #include <linux/compiler-gcc.h>
  51 #endif
  52
  53 #define notrace __attribute__((no_instrument_function))
  54
  55 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  56  * coming from above header files here
  57  */
  58 #ifdef __INTEL_COMPILER
  59 # include <linux/compiler-intel.h>
  60 #endif
  61
  62 /*
  63  * Generic compiler-dependent macros required for kernel
  64  * build go below this comment. Actual compiler/compiler version
  65  * specific implementations come from the above header files
  66  */
  67
  68 struct ftrace_branch_data {
  69         const char *func;
  70         const char *file;
  71         unsigned line;
  72         union {
  73                 struct {
  74                         unsigned long correct;
  75                         unsigned long incorrect;
  76                 };
  77                 struct {
  78                         unsigned long miss;
  79                         unsigned long hit;
  80                 };
  81                 unsigned long miss_hit[2];
  82         };
  83 };
  84
  85 /*
  86  * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
  87  * to disable branch tracing on a per file basis.
  88  */
  89 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
  90     && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
  91 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
  92
  93 #define likely_notrace(x)       __builtin_expect(!!(x), 1)
  94 #define unlikely_notrace(x)     __builtin_expect(!!(x), 0)
  95
  96 #define __branch_check__(x, expect) ({                                  \
  97                         int ______r;                                    \
  98                         static struct ftrace_branch_data                \
  99                                 __attribute__((__aligned__(4)))         \
 100                                 __attribute__((section("_ftrace_annotated_branch"))) \
 101                                 ______f = {                             \
 102                                 .func = __func__,                       \
 103                                 .file = __FILE__,                       \
 104                                 .line = __LINE__,                       \
 105                         };                                              \
 106                         ______r = likely_notrace(x);                    \
 107                         ftrace_likely_update(&______f, ______r, expect); \
 108                         ______r;                                        \
 109                 })
 110
 111 /*
 112  * Using __builtin_constant_p(x) to ignore cases where the return
 113  * value is always the same.  This idea is taken from a similar patch
 114  * written by Daniel Walker.
 115  */
 116 # ifndef likely
 117 #  define likely(x)     (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
 118 # endif
 119 # ifndef unlikely
 120 #  define unlikely(x)   (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
 121 # endif
 122
 123 #ifdef CONFIG_PROFILE_ALL_BRANCHES
 124 /*
 125  * "Define 'is'", Bill Clinton
 126  * "Define 'if'", Steven Rostedt
 127  */
 128 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
 129 #define __trace_if(cond) \
 130         if (__builtin_constant_p((cond)) ? !!(cond) :                   \
 131         ({                                                              \
 132                 int ______r;                                            \
 133                 static struct ftrace_branch_data                        \
 134                         __attribute__((__aligned__(4)))                 \
 135                         __attribute__((section("_ftrace_branch")))      \
 136                         ______f = {                                     \
 137                                 .func = __func__,                       \
 138                                 .file = __FILE__,                       \
 139                                 .line = __LINE__,                       \
 140                         };                                              \
 141                 ______r = !!(cond);                                     \
 142                 ______f.miss_hit[______r]++;                                    \
 143                 ______r;                                                \
 144         }))
 145 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
 146
 147 #else
 148 # define likely(x)      __builtin_expect(!!(x), 1)
 149 # define unlikely(x)    __builtin_expect(!!(x), 0)
 150 #endif
 151
 152 /* Optimization barrier */
 153 #ifndef barrier
 154 # define barrier() __memory_barrier()
 155 #endif
 156
 157 /* Unreachable code */
 158 #ifndef unreachable
 159 # define unreachable() do { } while (1)
 160 #endif
 161
 162 #ifndef RELOC_HIDE
 163 # define RELOC_HIDE(ptr, off)                                   \
 164   ({ unsigned long __ptr;                                       \
 165      __ptr = (unsigned long) (ptr);                             \
 166     (typeof(ptr)) (__ptr + (off)); })
 167 #endif
 168
 169 #endif /* __KERNEL__ */
 170
 171 #endif /* __ASSEMBLY__ */
 172
 173 #ifdef __KERNEL__
 174 /*
 175  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 176  * warning for each use, in hopes of speeding the functions removal.
 177  * Usage is:
 178  *              int __deprecated foo(void)
 179  */
 180 #ifndef __deprecated
 181 # define __deprecated           /* unimplemented */
 182 #endif
 183
 184 #ifdef MODULE
 185 #define __deprecated_for_modules __deprecated
 186 #else
 187 #define __deprecated_for_modules
 188 #endif
 189
 190 #ifndef __must_check
 191 #define __must_check
 192 #endif
 193
 194 #ifndef CONFIG_ENABLE_MUST_CHECK
 195 #undef __must_check
 196 #define __must_check
 197 #endif
 198 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
 199 #undef __deprecated
 200 #undef __deprecated_for_modules
 201 #define __deprecated
 202 #define __deprecated_for_modules
 203 #endif
 204
 205 /*
 206  * Allow us to avoid 'defined but not used' warnings on functions and data,
 207  * as well as force them to be emitted to the assembly file.
 208  *
 209  * As of gcc 3.4, static functions that are not marked with attribute((used))
 210  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 211  * marked will not be elided, but this may change in a future gcc version.
 212  *
 213  * NOTE: Because distributions shipped with a backported unit-at-a-time
 214  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 215  * for gcc >=3.3 instead of 3.4.
 216  *
 217  * In prior versions of gcc, such functions and data would be emitted, but
 218  * would be warned about except with attribute((unused)).
 219  *
 220  * Mark functions that are referenced only in inline assembly as __used so
 221  * the code is emitted even though it appears to be unreferenced.
 222  */
 223 #ifndef __used
 224 # define __used                 /* unimplemented */
 225 #endif
 226
 227 #ifndef __maybe_unused
 228 # define __maybe_unused         /* unimplemented */
 229 #endif
 230
 231 #ifndef __always_unused
 232 # define __always_unused        /* unimplemented */
 233 #endif
 234
 235 #ifndef noinline
 236 #define noinline
 237 #endif
 238
 239 /*
 240  * Rather then using noinline to prevent stack consumption, use
 241  * noinline_for_stack instead.  For documentation reasons.
 242  */
 243 #define noinline_for_stack noinline
 244
 245 #ifndef __always_inline
 246 #define __always_inline inline
 247 #endif
 248
 249 #endif /* __KERNEL__ */
 250
 251 /*
 252  * From the GCC manual:
 253  *
 254  * Many functions do not examine any values except their arguments,
 255  * and have no effects except the return value.  Basically this is
 256  * just slightly more strict class than the `pure' attribute above,
 257  * since function is not allowed to read global memory.
 258  *
 259  * Note that a function that has pointer arguments and examines the
 260  * data pointed to must _not_ be declared `const'.  Likewise, a
 261  * function that calls a non-`const' function usually must not be
 262  * `const'.  It does not make sense for a `const' function to return
 263  * `void'.
 264  */
 265 #ifndef __attribute_const__
 266 # define __attribute_const__    /* unimplemented */
 267 #endif
 268
 269 /*
 270  * Tell gcc if a function is cold. The compiler will assume any path
 271  * directly leading to the call is unlikely.
 272  */
 273
 274 #ifndef __cold
 275 #define __cold
 276 #endif
 277
 278 /* Simple shorthand for a section definition */
 279 #ifndef __section
 280 # define __section(S) __attribute__ ((__section__(#S)))
 281 #endif
 282
 283 #ifndef __visible
 284 #define __visible
 285 #endif
 286
 287 /* Are two types/vars the same type (ignoring qualifiers)? */
 288 #ifndef __same_type
 289 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
 290 #endif
 291
 292 /* Compile time object size, -1 for unknown */
 293 #ifndef __compiletime_object_size
 294 # define __compiletime_object_size(obj) -1
 295 #endif
 296 #ifndef __compiletime_warning
 297 # define __compiletime_warning(message)
 298 #endif
 299 #ifndef __compiletime_error
 300 # define __compiletime_error(message)
 301 #endif
 302 #ifndef __linktime_error
 303 # define __linktime_error(message)
 304 #endif
 305 /*
 306  * Prevent the compiler from merging or refetching accesses.  The compiler
 307  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 308  * but only when the compiler is aware of some particular ordering.  One way
 309  * to make the compiler aware of ordering is to put the two invocations of
 310  * ACCESS_ONCE() in different C statements.
 311  *
 312  * This macro does absolutely -nothing- to prevent the CPU from reordering,
 313  * merging, or refetching absolutely anything at any time.  Its main intended
 314  * use is to mediate communication between process-level code and irq/NMI
 315  * handlers, all running on the same CPU.
 316  */
 317 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 318
 319 #endif /* __LINUX_COMPILER_H */