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)
  18extern void __chk_user_ptr(const volatile void __user *);
  19extern 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
  58struct 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__)
  81void 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#ifndef RELOC_HIDE
 148# define RELOC_HIDE(ptr, off)                                   \
 149  ({ unsigned long __ptr;                                       \
 150     __ptr = (unsigned long) (ptr);                             \
 151    (typeof(ptr)) (__ptr + (off)); })
 152#endif
 153
 154#endif /* __KERNEL__ */
 155
 156#endif /* __ASSEMBLY__ */
 157
 158#ifdef __KERNEL__
 159/*
 160 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 161 * warning for each use, in hopes of speeding the functions removal.
 162 * Usage is:
 163 *              int __deprecated foo(void)
 164 */
 165#ifndef __deprecated
 166# define __deprecated           /* unimplemented */
 167#endif
 168
 169#ifdef MODULE
 170#define __deprecated_for_modules __deprecated
 171#else
 172#define __deprecated_for_modules
 173#endif
 174
 175#ifndef __must_check
 176#define __must_check
 177#endif
 178
 179#ifndef CONFIG_ENABLE_MUST_CHECK
 180#undef __must_check
 181#define __must_check
 182#endif
 183#ifndef CONFIG_ENABLE_WARN_DEPRECATED
 184#undef __deprecated
 185#undef __deprecated_for_modules
 186#define __deprecated
 187#define __deprecated_for_modules
 188#endif
 189
 190/*
 191 * Allow us to avoid 'defined but not used' warnings on functions and data,
 192 * as well as force them to be emitted to the assembly file.
 193 *
 194 * As of gcc 3.4, static functions that are not marked with attribute((used))
 195 * may be elided from the assembly file.  As of gcc 3.4, static data not so
 196 * marked will not be elided, but this may change in a future gcc version.
 197 *
 198 * NOTE: Because distributions shipped with a backported unit-at-a-time
 199 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 200 * for gcc >=3.3 instead of 3.4.
 201 *
 202 * In prior versions of gcc, such functions and data would be emitted, but
 203 * would be warned about except with attribute((unused)).
 204 *
 205 * Mark functions that are referenced only in inline assembly as __used so
 206 * the code is emitted even though it appears to be unreferenced.
 207 */
 208#ifndef __used
 209# define __used                 /* unimplemented */
 210#endif
 211
 212#ifndef __maybe_unused
 213# define __maybe_unused         /* unimplemented */
 214#endif
 215
 216#ifndef noinline
 217#define noinline
 218#endif
 219
 220/*
 221 * Rather then using noinline to prevent stack consumption, use
 222 * noinline_for_stack instead.  For documentaiton reasons.
 223 */
 224#define noinline_for_stack noinline
 225
 226#ifndef __always_inline
 227#define __always_inline inline
 228#endif
 229
 230#endif /* __KERNEL__ */
 231
 232/*
 233 * From the GCC manual:
 234 *
 235 * Many functions do not examine any values except their arguments,
 236 * and have no effects except the return value.  Basically this is
 237 * just slightly more strict class than the `pure' attribute above,
 238 * since function is not allowed to read global memory.
 239 *
 240 * Note that a function that has pointer arguments and examines the
 241 * data pointed to must _not_ be declared `const'.  Likewise, a
 242 * function that calls a non-`const' function usually must not be
 243 * `const'.  It does not make sense for a `const' function to return
 244 * `void'.
 245 */
 246#ifndef __attribute_const__
 247# define __attribute_const__    /* unimplemented */
 248#endif
 249
 250/*
 251 * Tell gcc if a function is cold. The compiler will assume any path
 252 * directly leading to the call is unlikely.
 253 */
 254
 255#ifndef __cold
 256#define __cold
 257#endif
 258
 259/* Simple shorthand for a section definition */
 260#ifndef __section
 261# define __section(S) __attribute__ ((__section__(#S)))
 262#endif
 263
 264/* Are two types/vars the same type (ignoring qualifiers)? */
 265#ifndef __same_type
 266# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
 267#endif
 268
 269/*
 270 * Prevent the compiler from merging or refetching accesses.  The compiler
 271 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 272 * but only when the compiler is aware of some particular ordering.  One way
 273 * to make the compiler aware of ordering is to put the two invocations of
 274 * ACCESS_ONCE() in different C statements.
 275 *
 276 * This macro does absolutely -nothing- to prevent the CPU from reordering,
 277 * merging, or refetching absolutely anything at any time.  Its main intended
 278 * use is to mediate communication between process-level code and irq/NMI
 279 * handlers, all running on the same CPU.
 280 */
 281#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 282
 283#endif /* __LINUX_COMPILER_H */
 284