LXR linux/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# define __percpu       __attribute__((noderef, address_space(3)))
  19extern void __chk_user_ptr(const volatile void __user *);
  20extern 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
  60struct 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__)
  83void 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 */
 306