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/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
*
* wrapper/compiler.h
*
* Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*/
#ifndef _LTTNG_WRAPPER_COMPILER_H
#define _LTTNG_WRAPPER_COMPILER_H
#include <linux/compiler.h>
#include <lttng/kernel-version.h>
/*
* Don't allow compiling with buggy compiler.
*/
#ifdef GCC_VERSION
/*
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58854
*/
# ifdef __ARMEL__
# if GCC_VERSION >= 40800 && GCC_VERSION <= 40802
# error Your gcc version produces clobbered frame accesses
# endif
# endif
/*
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
*/
# ifdef __aarch64__
# if GCC_VERSION < 50100
# error Your gcc version performs unsafe access to deallocated stack
# endif
# endif
#endif
/*
* READ/WRITE_ONCE were introduced in kernel 3.19 and ACCESS_ONCE
* was removed in 4.15. Prefer READ/WRITE but fallback to ACCESS
* when they are not available.
*/
#ifndef READ_ONCE
# define READ_ONCE(x) ACCESS_ONCE(x)
#endif
#ifndef WRITE_ONCE
# define WRITE_ONCE(x, val) ({ ACCESS_ONCE(x) = val; })
#endif
/*
* In v4.15 a smp read barrier was added to READ_ONCE to replace
* lockless_dereference(), replicate this behavior on prior kernels
* and remove calls to smp_read_barrier_depends which was dropped
* in v5.9.
*/
#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,15,0))
#define LTTNG_READ_ONCE(x) READ_ONCE(x)
#else
#define LTTNG_READ_ONCE(x) \
({ \
typeof(x) __val = READ_ONCE(x); \
smp_read_barrier_depends(); \
__val; \
})
#endif
#define __LTTNG_COMPOUND_LITERAL(type, ...) (type[]) { __VA_ARGS__ }
/*
* The static_assert macro was defined by the kernel in v5.1.
* If the macro is not defined, we define it.
* (kernel source: include/linux/build_bug.h)
*/
#ifndef static_assert
# define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
# define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
#endif
#endif /* _LTTNG_WRAPPER_COMPILER_H */
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