llvm/tools/llvm-exegesis/lib/MmapUtils.h

   1 //===-- MmapUtils.h ---------------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains compatibility-related preprocessor directives related
  10 // to mmap.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifdef __linux__
  15 #include <sys/mman.h>
  16 #include <sys/syscall.h>
  17
  18 // Before kernel 4.17, Linux did not support MAP_FIXED_NOREPLACE, so if it is
  19 // not available, simplfy define it as MAP_FIXED which performs the same
  20 // function but does not guarantee existing mappings won't get clobbered.
  21 #ifndef MAP_FIXED_NOREPLACE
  22 #define MAP_FIXED_NOREPLACE MAP_FIXED
  23 #endif
  24
  25 // Some 32-bit architectures don't have mmap and define mmap2 instead. The only
  26 // difference between the two syscalls is that mmap2's offset parameter is in
  27 // terms 4096 byte offsets rather than individual bytes, so for our purposes
  28 // they are effectively the same as all ofsets here are set to 0.
  29 #if defined(SYS_mmap2) && !defined(SYS_mmap)
  30 #define SYS_mmap SYS_mmap2
  31 #endif
  32 #endif // __linux__