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