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