| //===- Unix/Memory.cpp - Generic UNIX System Configuration ------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines some functions for various memory management utilities. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "Unix.h" |
| #include "llvm/System/Process.h" |
| |
| #ifdef HAVE_SYS_MMAN_H |
| #include <sys/mman.h> |
| #endif |
| |
| /// AllocateRWXMemory - Allocate a slab of memory with read/write/execute |
| /// permissions. This is typically used for JIT applications where we want |
| /// to emit code to the memory then jump to it. Getting this type of memory |
| /// is very OS specific. |
| /// |
| llvm::sys::MemoryBlock |
| llvm::sys::Memory::AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock, |
| std::string *ErrMsg) { |
| if (NumBytes == 0) return MemoryBlock(); |
| |
| long pageSize = Process::GetPageSize(); |
| unsigned NumPages = (NumBytes+pageSize-1)/pageSize; |
| |
| int fd = -1; |
| #ifdef NEED_DEV_ZERO_FOR_MMAP |
| static int zero_fd = open("/dev/zero", O_RDWR); |
| if (zero_fd == -1) { |
| MakeErrMsg(ErrMsg, "Can't open /dev/zero device"); |
| return MemoryBlock(); |
| } |
| fd = zero_fd; |
| #endif |
| |
| int flags = MAP_PRIVATE | |
| #ifdef HAVE_MMAP_ANONYMOUS |
| MAP_ANONYMOUS |
| #else |
| MAP_ANON |
| #endif |
| ; |
| |
| void* start = NearBlock ? (unsigned char*)NearBlock->base() + |
| NearBlock->size() : 0; |
| |
| void *pa = ::mmap(start, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC, |
| flags, fd, 0); |
| if (pa == MAP_FAILED) { |
| if (NearBlock) //Try again without a near hint |
| return AllocateRWX(NumBytes, 0); |
| |
| MakeErrMsg(ErrMsg, "Can't allocate RWX Memory"); |
| return MemoryBlock(); |
| } |
| MemoryBlock result; |
| result.Address = pa; |
| result.Size = NumPages*pageSize; |
| return result; |
| } |
| |
| bool llvm::sys::Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) { |
| if (M.Address == 0 || M.Size == 0) return false; |
| if (0 != ::munmap(M.Address, M.Size)) |
| return MakeErrMsg(ErrMsg, "Can't release RWX Memory"); |
| return false; |
| } |
| |