root/tools/lib/bpf/libbpf_util.h

INCLUDED FROM

   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
  10 extern "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