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