1 //===---------- Linux implementation of the POSIX posix_madvise function --===// 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 #include "src/sys/mman/posix_madvise.h" 10 11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function. 12 #include "src/__support/common.h" 13 14 #include <sys/syscall.h> // For syscall numbers. 15 16 namespace LIBC_NAMESPACE { 17 18 // This function is currently linux only. It has to be refactored suitably if 19 // posix_madvise is to be supported on non-linux operating systems also. 20 LLVM_LIBC_FUNCTION(int, posix_madvise, (void *addr, size_t size, int advice)) { 21 // POSIX_MADV_DONTNEED does nothing because the default MADV_DONTNEED may 22 // cause data loss, which the posix madvise does not allow. 23 if (advice == POSIX_MADV_DONTNEED) { 24 return 0; 25 } 26 int ret = LIBC_NAMESPACE::syscall_impl<int>( 27 SYS_madvise, reinterpret_cast<long>(addr), size, advice); 28 return ret < 0 ? -ret : 0; 29 } 30 31 } // namespace LIBC_NAMESPACE 32