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 #include "src/__support/macros/config.h" 14 15 #include <sys/syscall.h> // For syscall numbers. 16 17 namespace LIBC_NAMESPACE_DECL { 18 19 // This function is currently linux only. It has to be refactored suitably if 20 // posix_madvise is to be supported on non-linux operating systems also. 21 LLVM_LIBC_FUNCTION(int, posix_madvise, (void *addr, size_t size, int advice)) { 22 // POSIX_MADV_DONTNEED does nothing because the default MADV_DONTNEED may 23 // cause data loss, which the posix madvise does not allow. 24 if (advice == POSIX_MADV_DONTNEED) { 25 return 0; 26 } 27 int ret = LIBC_NAMESPACE::syscall_impl<int>( 28 SYS_madvise, reinterpret_cast<long>(addr), size, advice); 29 return ret < 0 ? -ret : 0; 30 } 31 32 } // namespace LIBC_NAMESPACE_DECL 33