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//===- Unix/Memory.cpp - Generic UNIX System Configuration ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Reid Spencer and 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) {
GetErrno("Can't open /dev/zero device", ErrMsg);
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);
GetErrno("Can't allocate RWX Memory", ErrMsg);
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 GetErrno("Can't release RWX Memory", ErrMsg);
return false;
}
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