root/include/linux/compiler.h

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#ifndef __LINUX_COMPILER_H
#define __LINUX_COMPILER_H

#ifndef __ASSEMBLY__

#ifdef __CHECKER__
# define __user         __attribute__((noderef, address_space(1)))
# define __kernel       __attribute__((address_space(0)))
# define __safe         __attribute__((safe))
# define __force        __attribute__((force))
# define __nocast       __attribute__((nocast))
# define __iomem        __attribute__((noderef, address_space(2)))
# define __must_hold(x) __attribute__((context(x,1,1)))
# define __acquires(x)  __attribute__((context(x,0,1)))
# define __releases(x)  __attribute__((context(x,1,0)))
# define __acquire(x)   __context__(x,1)
# define __release(x)   __context__(x,-1)
# define __cond_lock(x,c)       ((c) ? ({ __acquire(x); 1; }) : 0)
# define __percpu       __attribute__((noderef, address_space(3)))
#ifdef CONFIG_SPARSE_RCU_POINTER
# define __rcu          __attribute__((noderef, address_space(4)))
#else
# define __rcu
#endif
extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);
#else
# define __user
# define __kernel
# define __safe
# define __force
# define __nocast
# define __iomem
# define __chk_user_ptr(x) (void)0
# define __chk_io_ptr(x) (void)0
# define __builtin_warning(x, y...) (1)
# define __must_hold(x)
# define __acquires(x)
# define __releases(x)
# define __acquire(x) (void)0
# define __release(x) (void)0
# define __cond_lock(x,c) (c)
# define __percpu
# define __rcu
#endif

/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
#define ___PASTE(a,b) a##b
#define __PASTE(a,b) ___PASTE(a,b)

#ifdef __KERNEL__

#ifdef __GNUC__
#include <linux/compiler-gcc.h>
#endif

#define notrace __attribute__((no_instrument_function))

/* Intel compiler defines __GNUC__. So we will overwrite implementations
 * coming from above header files here
 */
#ifdef __INTEL_COMPILER
# include <linux/compiler-intel.h>
#endif

/* Clang compiler defines __GNUC__. So we will overwrite implementations
 * coming from above header files here
 */
#ifdef __clang__
#include <linux/compiler-clang.h>
#endif

/*
 * Generic compiler-dependent macros required for kernel
 * build go below this comment. Actual compiler/compiler version
 * specific implementations come from the above header files
 */

struct ftrace_branch_data {
        const char *func;
        const char *file;
        unsigned line;
        union {
                struct {
                        unsigned long correct;
                        unsigned long incorrect;
                };
                struct {
                        unsigned long miss;
                        unsigned long hit;
                };
                unsigned long miss_hit[2];
        };
};

/*
 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
 * to disable branch tracing on a per file basis.
 */
#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
    && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);

#define likely_notrace(x)       __builtin_expect(!!(x), 1)
#define unlikely_notrace(x)     __builtin_expect(!!(x), 0)

#define __branch_check__(x, expect) ({                                  \
                        int ______r;                                    \
                        static struct ftrace_branch_data                \
                                __attribute__((__aligned__(4)))         \
                                __attribute__((section("_ftrace_annotated_branch"))) \
                                ______f = {                             \
                                .func = __func__,                       \
                                .file = __FILE__,                       \
                                .line = __LINE__,                       \
                        };                                              \
                        ______r = likely_notrace(x);                    \
                        ftrace_likely_update(&______f, ______r, expect); \
                        ______r;                                        \
                })

/*
 * Using __builtin_constant_p(x) to ignore cases where the return
 * value is always the same.  This idea is taken from a similar patch
 * written by Daniel Walker.
 */
# ifndef likely
#  define likely(x)     (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
# endif
# ifndef unlikely
#  define unlikely(x)   (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
# endif

#ifdef CONFIG_PROFILE_ALL_BRANCHES
/*
 * "Define 'is'", Bill Clinton
 * "Define 'if'", Steven Rostedt
 */
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
#define __trace_if(cond) \
        if (__builtin_constant_p((cond)) ? !!(cond) :                   \
        ({                                                              \
                int ______r;                                            \
                static struct ftrace_branch_data                        \
                        __attribute__((__aligned__(4)))                 \
                        __attribute__((section("_ftrace_branch")))      \
                        ______f = {                                     \
                                .func = __func__,                       \
                                .file = __FILE__,                       \
                                .line = __LINE__,                       \
                        };                                              \
                ______r = !!(cond);                                     \
                ______f.miss_hit[______r]++;                                    \
                ______r;                                                \
        }))
#endif /* CONFIG_PROFILE_ALL_BRANCHES */

#else
# define likely(x)      __builtin_expect(!!(x), 1)
# define unlikely(x)    __builtin_expect(!!(x), 0)
#endif

/* Optimization barrier */
#ifndef barrier
# define barrier() __memory_barrier()
#endif

/* Unreachable code */
#ifndef unreachable
# define unreachable() do { } while (1)
#endif

#ifndef RELOC_HIDE
# define RELOC_HIDE(ptr, off)                                   \
  ({ unsigned long __ptr;                                       \
     __ptr = (unsigned long) (ptr);                             \
    (typeof(ptr)) (__ptr + (off)); })
#endif

#ifndef OPTIMIZER_HIDE_VAR
#define OPTIMIZER_HIDE_VAR(var) barrier()
#endif

/* Not-quite-unique ID. */
#ifndef __UNIQUE_ID
# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
#endif

#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */

#ifdef __KERNEL__
/*
 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 * warning for each use, in hopes of speeding the functions removal.
 * Usage is:
 *              int __deprecated foo(void)
 */
#ifndef __deprecated
# define __deprecated           /* unimplemented */
#endif

#ifdef MODULE
#define __deprecated_for_modules __deprecated
#else
#define __deprecated_for_modules
#endif

#ifndef __must_check
#define __must_check
#endif

#ifndef CONFIG_ENABLE_MUST_CHECK
#undef __must_check
#define __must_check
#endif
#ifndef CONFIG_ENABLE_WARN_DEPRECATED
#undef __deprecated
#undef __deprecated_for_modules
#define __deprecated
#define __deprecated_for_modules
#endif

/*
 * Allow us to avoid 'defined but not used' warnings on functions and data,
 * as well as force them to be emitted to the assembly file.
 *
 * As of gcc 3.4, static functions that are not marked with attribute((used))
 * may be elided from the assembly file.  As of gcc 3.4, static data not so
 * marked will not be elided, but this may change in a future gcc version.
 *
 * NOTE: Because distributions shipped with a backported unit-at-a-time
 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 * for gcc >=3.3 instead of 3.4.
 *
 * In prior versions of gcc, such functions and data would be emitted, but
 * would be warned about except with attribute((unused)).
 *
 * Mark functions that are referenced only in inline assembly as __used so
 * the code is emitted even though it appears to be unreferenced.
 */
#ifndef __used
# define __used                 /* unimplemented */
#endif

#ifndef __maybe_unused
# define __maybe_unused         /* unimplemented */
#endif

#ifndef __always_unused
# define __always_unused        /* unimplemented */
#endif

#ifndef noinline
#define noinline
#endif

/*
 * Rather then using noinline to prevent stack consumption, use
 * noinline_for_stack instead.  For documentation reasons.
 */
#define noinline_for_stack noinline

#ifndef __always_inline
#define __always_inline inline
#endif

#endif /* __KERNEL__ */

/*
 * From the GCC manual:
 *
 * Many functions do not examine any values except their arguments,
 * and have no effects except the return value.  Basically this is
 * just slightly more strict class than the `pure' attribute above,
 * since function is not allowed to read global memory.
 *
 * Note that a function that has pointer arguments and examines the
 * data pointed to must _not_ be declared `const'.  Likewise, a
 * function that calls a non-`const' function usually must not be
 * `const'.  It does not make sense for a `const' function to return
 * `void'.
 */
#ifndef __attribute_const__
# define __attribute_const__    /* unimplemented */
#endif

/*
 * Tell gcc if a function is cold. The compiler will assume any path
 * directly leading to the call is unlikely.
 */

#ifndef __cold
#define __cold
#endif

/* Simple shorthand for a section definition */
#ifndef __section
# define __section(S) __attribute__ ((__section__(#S)))
#endif

#ifndef __visible
#define __visible
#endif

/* Are two types/vars the same type (ignoring qualifiers)? */
#ifndef __same_type
# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
#endif

/* Is this type a native word size -- useful for atomic operations */
#ifndef __native_word
# define __native_word(t) (sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
#endif

/* Compile time object size, -1 for unknown */
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
#endif
#ifndef __compiletime_warning
# define __compiletime_warning(message)
#endif
#ifndef __compiletime_error
# define __compiletime_error(message)
/*
 * Sparse complains of variable sized arrays due to the temporary variable in
 * __compiletime_assert. Unfortunately we can't just expand it out to make
 * sparse see a constant array size without breaking compiletime_assert on old
 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
 */
# ifndef __CHECKER__
#  define __compiletime_error_fallback(condition) \
        do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
# endif
#endif
#ifndef __compiletime_error_fallback
# define __compiletime_error_fallback(condition) do { } while (0)
#endif

#define __compiletime_assert(condition, msg, prefix, suffix)            \
        do {                                                            \
                bool __cond = !(condition);                             \
                extern void prefix ## suffix(void) __compiletime_error(msg); \
                if (__cond)                                             \
                        prefix ## suffix();                             \
                __compiletime_error_fallback(__cond);                   \
        } while (0)

#define _compiletime_assert(condition, msg, prefix, suffix) \
        __compiletime_assert(condition, msg, prefix, suffix)

/**
 * compiletime_assert - break build and emit msg if condition is false
 * @condition: a compile-time constant condition to check
 * @msg:       a message to emit if condition is false
 *
 * In tradition of POSIX assert, this macro will break the build if the
 * supplied condition is *false*, emitting the supplied error message if the
 * compiler has support to do so.
 */
#define compiletime_assert(condition, msg) \
        _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)

#define compiletime_assert_atomic_type(t)                               \
        compiletime_assert(__native_word(t),                            \
                "Need native word sized stores/loads for atomicity.")

/*
 * Prevent the compiler from merging or refetching accesses.  The compiler
 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 * but only when the compiler is aware of some particular ordering.  One way
 * to make the compiler aware of ordering is to put the two invocations of
 * ACCESS_ONCE() in different C statements.
 *
 * This macro does absolutely -nothing- to prevent the CPU from reordering,
 * merging, or refetching absolutely anything at any time.  Its main intended
 * use is to mediate communication between process-level code and irq/NMI
 * handlers, all running on the same CPU.
 */
#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))

/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
#ifdef CONFIG_KPROBES
# define __kprobes      __attribute__((__section__(".kprobes.text")))
# define nokprobe_inline        __always_inline
#else
# define __kprobes
# define nokprobe_inline        inline
#endif
#endif /* __LINUX_COMPILER_H */

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