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 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
  48 #define ___PASTE(a,b) a##b
  49 #define __PASTE(a,b) ___PASTE(a,b)
  50
  51 #ifdef __KERNEL__
  52
  53 #ifdef __GNUC__
  54 #include <linux/compiler-gcc.h>
  55 #endif
  56
  57 #define notrace __attribute__((no_instrument_function))
  58
  59 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  60  * coming from above header files here
  61  */
  62 #ifdef __INTEL_COMPILER
  63 # include <linux/compiler-intel.h>
  64 #endif
  65
  66 /*
  67  * Generic compiler-dependent macros required for kernel
  68  * build go below this comment. Actual compiler/compiler version
  69  * specific implementations come from the above header files
  70  */
  71
  72 struct ftrace_branch_data {
  73         const char *func;
  74         const char *file;
  75         unsigned line;
  76         union {
  77                 struct {
  78                         unsigned long correct;
  79                         unsigned long incorrect;
  80                 };
  81                 struct {
  82                         unsigned long miss;
  83                         unsigned long hit;
  84                 };
  85                 unsigned long miss_hit[2];
  86         };
  87 };
  88
  89 /*
  90  * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
  91  * to disable branch tracing on a per file basis.
  92  */
  93 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
  94     && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
  95 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
  96
  97 #define likely_notrace(x)       __builtin_expect(!!(x), 1)
  98 #define unlikely_notrace(x)     __builtin_expect(!!(x), 0)
  99
 100 #define __branch_check__(x, expect) ({                                  \
 101                         int ______r;                                    \
 102                         static struct ftrace_branch_data                \
 103                                 __attribute__((__aligned__(4)))         \
 104                                 __attribute__((section("_ftrace_annotated_branch"))) \
 105                                 ______f = {                             \
 106                                 .func = __func__,                       \
 107                                 .file = __FILE__,                       \
 108                                 .line = __LINE__,                       \
 109                         };                                              \
 110                         ______r = likely_notrace(x);                    \
 111                         ftrace_likely_update(&______f, ______r, expect); \
 112                         ______r;                                        \
 113                 })
 114
 115 /*
 116  * Using __builtin_constant_p(x) to ignore cases where the return
 117  * value is always the same.  This idea is taken from a similar patch
 118  * written by Daniel Walker.
 119  */
 120 # ifndef likely
 121 #  define likely(x)     (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
 122 # endif
 123 # ifndef unlikely
 124 #  define unlikely(x)   (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
 125 # endif
 126
 127 #ifdef CONFIG_PROFILE_ALL_BRANCHES
 128 /*
 129  * "Define 'is'", Bill Clinton
 130  * "Define 'if'", Steven Rostedt
 131  */
 132 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
 133 #define __trace_if(cond) \
 134         if (__builtin_constant_p(!!(cond)) ? !!(cond) :                 \
 135         ({                                                              \
 136                 int ______r;                                            \
 137                 static struct ftrace_branch_data                        \
 138                         __attribute__((__aligned__(4)))                 \
 139                         __attribute__((section("_ftrace_branch")))      \
 140                         ______f = {                                     \
 141                                 .func = __func__,                       \
 142                                 .file = __FILE__,                       \
 143                                 .line = __LINE__,                       \
 144                         };                                              \
 145                 ______r = !!(cond);                                     \
 146                 ______f.miss_hit[______r]++;                                    \
 147                 ______r;                                                \
 148         }))
 149 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
 150
 151 #else
 152 # define likely(x)      __builtin_expect(!!(x), 1)
 153 # define unlikely(x)    __builtin_expect(!!(x), 0)
 154 #endif
 155
 156 /* Optimization barrier */
 157 #ifndef barrier
 158 # define barrier() __memory_barrier()
 159 #endif
 160
 161 /* Unreachable code */
 162 #ifndef unreachable
 163 # define unreachable() do { } while (1)
 164 #endif
 165
 166 #ifndef RELOC_HIDE
 167 # define RELOC_HIDE(ptr, off)                                   \
 168   ({ unsigned long __ptr;                                       \
 169      __ptr = (unsigned long) (ptr);                             \
 170     (typeof(ptr)) (__ptr + (off)); })
 171 #endif
 172
 173 #ifndef OPTIMIZER_HIDE_VAR
 174 #define OPTIMIZER_HIDE_VAR(var) barrier()
 175 #endif
 176
 177 /* Not-quite-unique ID. */
 178 #ifndef __UNIQUE_ID
 179 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
 180 #endif
 181
 182 #endif /* __KERNEL__ */
 183
 184 #endif /* __ASSEMBLY__ */
 185
 186 #ifdef __KERNEL__
 187 /*
 188  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 189  * warning for each use, in hopes of speeding the functions removal.
 190  * Usage is:
 191  *              int __deprecated foo(void)
 192  */
 193 #ifndef __deprecated
 194 # define __deprecated           /* unimplemented */
 195 #endif
 196
 197 #ifdef MODULE
 198 #define __deprecated_for_modules __deprecated
 199 #else
 200 #define __deprecated_for_modules
 201 #endif
 202
 203 #ifndef __must_check
 204 #define __must_check
 205 #endif
 206
 207 #ifndef CONFIG_ENABLE_MUST_CHECK
 208 #undef __must_check
 209 #define __must_check
 210 #endif
 211 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
 212 #undef __deprecated
 213 #undef __deprecated_for_modules
 214 #define __deprecated
 215 #define __deprecated_for_modules
 216 #endif
 217
 218 /*
 219  * Allow us to avoid 'defined but not used' warnings on functions and data,
 220  * as well as force them to be emitted to the assembly file.
 221  *
 222  * As of gcc 3.4, static functions that are not marked with attribute((used))
 223  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 224  * marked will not be elided, but this may change in a future gcc version.
 225  *
 226  * NOTE: Because distributions shipped with a backported unit-at-a-time
 227  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 228  * for gcc >=3.3 instead of 3.4.
 229  *
 230  * In prior versions of gcc, such functions and data would be emitted, but
 231  * would be warned about except with attribute((unused)).
 232  *
 233  * Mark functions that are referenced only in inline assembly as __used so
 234  * the code is emitted even though it appears to be unreferenced.
 235  */
 236 #ifndef __used
 237 # define __used                 /* unimplemented */
 238 #endif
 239
 240 #ifndef __maybe_unused
 241 # define __maybe_unused         /* unimplemented */
 242 #endif
 243
 244 #ifndef __always_unused
 245 # define __always_unused        /* unimplemented */
 246 #endif
 247
 248 #ifndef noinline
 249 #define noinline
 250 #endif
 251
 252 /*
 253  * Rather then using noinline to prevent stack consumption, use
 254  * noinline_for_stack instead.  For documentation reasons.
 255  */
 256 #define noinline_for_stack noinline
 257
 258 #ifndef __always_inline
 259 #define __always_inline inline
 260 #endif
 261
 262 #endif /* __KERNEL__ */
 263
 264 /*
 265  * From the GCC manual:
 266  *
 267  * Many functions do not examine any values except their arguments,
 268  * and have no effects except the return value.  Basically this is
 269  * just slightly more strict class than the `pure' attribute above,
 270  * since function is not allowed to read global memory.
 271  *
 272  * Note that a function that has pointer arguments and examines the
 273  * data pointed to must _not_ be declared `const'.  Likewise, a
 274  * function that calls a non-`const' function usually must not be
 275  * `const'.  It does not make sense for a `const' function to return
 276  * `void'.
 277  */
 278 #ifndef __attribute_const__
 279 # define __attribute_const__    /* unimplemented */
 280 #endif
 281
 282 /*
 283  * Tell gcc if a function is cold. The compiler will assume any path
 284  * directly leading to the call is unlikely.
 285  */
 286
 287 #ifndef __cold
 288 #define __cold
 289 #endif
 290
 291 /* Simple shorthand for a section definition */
 292 #ifndef __section
 293 # define __section(S) __attribute__ ((__section__(#S)))
 294 #endif
 295
 296 #ifndef __visible
 297 #define __visible
 298 #endif
 299
 300 /* Are two types/vars the same type (ignoring qualifiers)? */
 301 #ifndef __same_type
 302 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
 303 #endif
 304
 305 /* Compile time object size, -1 for unknown */
 306 #ifndef __compiletime_object_size
 307 # define __compiletime_object_size(obj) -1
 308 #endif
 309 #ifndef __compiletime_warning
 310 # define __compiletime_warning(message)
 311 #endif
 312 #ifndef __compiletime_error
 313 # define __compiletime_error(message)
 314 # define __compiletime_error_fallback(condition) \
 315         do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
 316 #else
 317 # define __compiletime_error_fallback(condition) do { } while (0)
 318 #endif
 319
 320 #define __compiletime_assert(condition, msg, prefix, suffix)            \
 321         do {                                                            \
 322                 bool __cond = !(condition);                             \
 323                 extern void prefix ## suffix(void) __compiletime_error(msg); \
 324                 if (__cond)                                             \
 325                         prefix ## suffix();                             \
 326                 __compiletime_error_fallback(__cond);                   \
 327         } while (0)
 328
 329 #define _compiletime_assert(condition, msg, prefix, suffix) \
 330         __compiletime_assert(condition, msg, prefix, suffix)
 331
 332 /**
 333  * compiletime_assert - break build and emit msg if condition is false
 334  * @condition: a compile-time constant condition to check
 335  * @msg:       a message to emit if condition is false
 336  *
 337  * In tradition of POSIX assert, this macro will break the build if the
 338  * supplied condition is *false*, emitting the supplied error message if the
 339  * compiler has support to do so.
 340  */
 341 #define compiletime_assert(condition, msg) \
 342         _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
 343
 344 /*
 345  * Prevent the compiler from merging or refetching accesses.  The compiler
 346  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 347  * but only when the compiler is aware of some particular ordering.  One way
 348  * to make the compiler aware of ordering is to put the two invocations of
 349  * ACCESS_ONCE() in different C statements.
 350  *
 351  * This macro does absolutely -nothing- to prevent the CPU from reordering,
 352  * merging, or refetching absolutely anything at any time.  Its main intended
 353  * use is to mediate communication between process-level code and irq/NMI
 354  * handlers, all running on the same CPU.
 355  */
 356 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 357
 358 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
 359 #ifdef CONFIG_KPROBES
 360 # define __kprobes      __attribute__((__section__(".kprobes.text")))
 361 #else
 362 # define __kprobes
 363 #endif
 364 #endif /* __LINUX_COMPILER_H */