1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
 2/* Copyright (c) 2019 Facebook */
 3
 4#ifndef __LIBBPF_LIBBPF_UTIL_H
 5#define __LIBBPF_LIBBPF_UTIL_H
 6
 7#include <stdbool.h>
 8
 9#ifdef __cplusplus
10extern "C" {
11#endif
12
13/* Use these barrier functions instead of smp_[rw]mb() when they are
14 * used in a libbpf header file. That way they can be built into the
15 * application that uses libbpf.
16 */
17#if defined(__i386__) || defined(__x86_64__)
18# define libbpf_smp_rmb() asm volatile("" : : : "memory")
19# define libbpf_smp_wmb() asm volatile("" : : : "memory")
20# define libbpf_smp_mb() \
21	asm volatile("lock; addl $0,-4(%%rsp)" : : : "memory", "cc")
22/* Hinders stores to be observed before older loads. */
23# define libbpf_smp_rwmb() asm volatile("" : : : "memory")
24#elif defined(__aarch64__)
25# define libbpf_smp_rmb() asm volatile("dmb ishld" : : : "memory")
26# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
27# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory")
28# define libbpf_smp_rwmb() libbpf_smp_mb()
29#elif defined(__arm__)
30/* These are only valid for armv7 and above */
31# define libbpf_smp_rmb() asm volatile("dmb ish" : : : "memory")
32# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
33# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory")
34# define libbpf_smp_rwmb() libbpf_smp_mb()
35#else
36/* Architecture missing native barrier functions. */
37# define libbpf_smp_rmb() __sync_synchronize()
38# define libbpf_smp_wmb() __sync_synchronize()
39# define libbpf_smp_mb() __sync_synchronize()
40# define libbpf_smp_rwmb() __sync_synchronize()
41#endif
42
43#ifdef __cplusplus
44} /* extern "C" */
45#endif
46
47#endif