tcp: take care of truncations done by sk_filter()

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / include / linux / compiler-gcc.h

#ifndef __LINUX_COMPILER_H
#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
#endif

/*
 * Common definitions for all gcc versions go here.
 */
#define GCC_VERSION (__GNUC__ * 10000 \
		   + __GNUC_MINOR__ * 100 \
		   + __GNUC_PATCHLEVEL__)


/* Optimization barrier */
/* The "volatile" is due to gcc bugs */
#define barrier() __asm__ __volatile__("": : :"memory")

/*
 * This macro obfuscates arithmetic on a variable address so that gcc
 * shouldn't recognize the original var, and make assumptions about it.
 *
 * This is needed because the C standard makes it undefined to do
 * pointer arithmetic on "objects" outside their boundaries and the
 * gcc optimizers assume this is the case. In particular they
 * assume such arithmetic does not wrap.
 *
 * A miscompilation has been observed because of this on PPC.
 * To work around it we hide the relationship of the pointer and the object
 * using this macro.
 *
 * Versions of the ppc64 compiler before 4.1 had a bug where use of
 * RELOC_HIDE could trash r30. The bug can be worked around by changing
 * the inline assembly constraint from =g to =r, in this particular
 * case either is valid.
 */
#define RELOC_HIDE(ptr, off)					\
  ({ unsigned long __ptr;					\
    __asm__ ("" : "=r"(__ptr) : "0"(ptr));		\
    (typeof(ptr)) (__ptr + (off)); })

/* Make the optimizer believe the variable can be manipulated arbitrarily. */
#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var))

#ifdef __CHECKER__
#define __must_be_array(arr) 0
#else
/* &a[0] degrades to a pointer: a different type from an array */
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
#endif

/*
 * Force always-inline if the user requests it so via the .config,
 * or if gcc is too old:
 */
#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
# define inline		inline		__attribute__((always_inline)) notrace
# define __inline__	__inline__	__attribute__((always_inline)) notrace
# define __inline	__inline	__attribute__((always_inline)) notrace
#else
/* A lot of inline functions can cause havoc with function tracing */
# define inline		inline		notrace
# define __inline__	__inline__	notrace
# define __inline	__inline	notrace
#endif

#define __deprecated			__attribute__((deprecated))
#define __packed			__attribute__((packed))
#define __weak				__attribute__((weak))

/*
 * it doesn't make sense on ARM (currently the only user of __naked) to trace
 * naked functions because then mcount is called without stack and frame pointer
 * being set up and there is no chance to restore the lr register to the value
 * before mcount was called.
 *
 * The asm() bodies of naked functions often depend on standard calling conventions,
 * therefore they must be noinline and noclone.  GCC 4.[56] currently fail to enforce
 * this, so we must do so ourselves.  See GCC PR44290.
 */
#define __naked				__attribute__((naked)) noinline __noclone notrace

#define __noreturn			__attribute__((noreturn))

/*
 * From the GCC manual:
 *
 * Many functions have no effects except the return value and their
 * return value depends only on the parameters and/or global
 * variables.  Such a function can be subject to common subexpression
 * elimination and loop optimization just as an arithmetic operator
 * would be.
 * [...]
 */
#define __pure				__attribute__((pure))
#define __aligned(x)			__attribute__((aligned(x)))
#define __printf(a, b)			__attribute__((format(printf, a, b)))
#define __scanf(a, b)			__attribute__((format(scanf, a, b)))
#define  noinline			__attribute__((noinline))
#define __attribute_const__		__attribute__((__const__))
#define __maybe_unused			__attribute__((unused))
#define __always_unused			__attribute__((unused))

/* gcc version specific checks */

#if GCC_VERSION < 30200
# error Sorry, your compiler is too old - please upgrade it.
#endif

#if GCC_VERSION < 30300
# define __used			__attribute__((__unused__))
#else
# define __used			__attribute__((__used__))
#endif

#ifdef CONFIG_GCOV_KERNEL
# if GCC_VERSION < 30400
#   error "GCOV profiling support for gcc versions below 3.4 not included"
# endif /* __GNUC_MINOR__ */
#endif /* CONFIG_GCOV_KERNEL */

#if GCC_VERSION >= 30400
#define __must_check		__attribute__((warn_unused_result))
#endif

#if GCC_VERSION >= 40000

/* GCC 4.1.[01] miscompiles __weak */
#ifdef __KERNEL__
# if GCC_VERSION >= 40100 &&  GCC_VERSION <= 40101
#  error Your version of gcc miscompiles the __weak directive
# endif
#endif

#define __used			__attribute__((__used__))
#define __compiler_offsetof(a, b)					\
	__builtin_offsetof(a, b)

#if GCC_VERSION >= 40100 && GCC_VERSION < 40600
# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
#endif

#if GCC_VERSION >= 40300
/* Mark functions as cold. gcc will assume any path leading to a call
 * to them will be unlikely.  This means a lot of manual unlikely()s
 * are unnecessary now for any paths leading to the usual suspects
 * like BUG(), printk(), panic() etc. [but let's keep them for now for
 * older compilers]
 *
 * Early snapshots of gcc 4.3 don't support this and we can't detect this
 * in the preprocessor, but we can live with this because they're unreleased.
 * Maketime probing would be overkill here.
 *
 * gcc also has a __attribute__((__hot__)) to move hot functions into
 * a special section, but I don't see any sense in this right now in
 * the kernel context
 */
#define __cold			__attribute__((__cold__))

#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)

#ifndef __CHECKER__
# define __compiletime_warning(message) __attribute__((warning(message)))
# define __compiletime_error(message) __attribute__((error(message)))
#endif /* __CHECKER__ */
#endif /* GCC_VERSION >= 40300 */

#if GCC_VERSION >= 40500
/*
 * Mark a position in code as unreachable.  This can be used to
 * suppress control flow warnings after asm blocks that transfer
 * control elsewhere.
 *
 * Early snapshots of gcc 4.5 don't support this and we can't detect
 * this in the preprocessor, but we can live with this because they're
 * unreleased.  Really, we need to have autoconf for the kernel.
 */
#define unreachable() __builtin_unreachable()

/* Mark a function definition as prohibited from being cloned. */
#define __noclone	__attribute__((__noclone__, __optimize__("no-tracer")))

#endif /* GCC_VERSION >= 40500 */

#if GCC_VERSION >= 40600
/*
 * Tell the optimizer that something else uses this function or variable.
 */
#define __visible	__attribute__((externally_visible))
#endif

/*
 * GCC 'asm goto' miscompiles certain code sequences:
 *
 *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
 *
 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
 *
 * (asm goto is automatically volatile - the naming reflects this.)
 */
#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)

#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
#if GCC_VERSION >= 40400
#define __HAVE_BUILTIN_BSWAP32__
#define __HAVE_BUILTIN_BSWAP64__
#endif
#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
#define __HAVE_BUILTIN_BSWAP16__
#endif
#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */

#endif	/* gcc version >= 40000 specific checks */

#if !defined(__noclone)
#define __noclone	/* not needed */
#endif

/*
 * A trick to suppress uninitialized variable warning without generating any
 * code
 */
#define uninitialized_var(x) x = x

#define __always_inline		inline __attribute__((always_inline))