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//===- Win32/Memory.cpp - Win32 Memory Implementation -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides the Win32 specific implementation of various Memory
// management utilities
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/WindowsError.h"
// The Windows.h header must be the last one included.
#include "WindowsSupport.h"
using std::error_code;
namespace {
DWORD getWindowsProtectionFlags(unsigned Flags) {
switch (Flags) {
// Contrary to what you might expect, the Windows page protection flags
// are not a bitwise combination of RWX values
case llvm::sys::Memory::MF_READ:
return PAGE_READONLY;
case llvm::sys::Memory::MF_WRITE:
// Note: PAGE_WRITE is not supported by VirtualProtect
return PAGE_READWRITE;
case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
return PAGE_READWRITE;
case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
return PAGE_EXECUTE_READ;
case llvm::sys::Memory::MF_READ |
llvm::sys::Memory::MF_WRITE |
llvm::sys::Memory::MF_EXEC:
return PAGE_EXECUTE_READWRITE;
case llvm::sys::Memory::MF_EXEC:
return PAGE_EXECUTE;
default:
llvm_unreachable("Illegal memory protection flag specified!");
}
// Provide a default return value as required by some compilers.
return PAGE_NOACCESS;
}
size_t getAllocationGranularity() {
SYSTEM_INFO Info;
::GetSystemInfo(&Info);
if (Info.dwPageSize > Info.dwAllocationGranularity)
return Info.dwPageSize;
else
return Info.dwAllocationGranularity;
}
} // namespace
namespace llvm {
namespace sys {
//===----------------------------------------------------------------------===//
//=== WARNING: Implementation here must contain only Win32 specific code
//=== and must not be UNIX code
//===----------------------------------------------------------------------===//
MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
const MemoryBlock *const NearBlock,
unsigned Flags,
error_code &EC) {
EC = error_code();
if (NumBytes == 0)
return MemoryBlock();
// While we'd be happy to allocate single pages, the Windows allocation
// granularity may be larger than a single page (in practice, it is 64K)
// so mapping less than that will create an unreachable fragment of memory.
static const size_t Granularity = getAllocationGranularity();
const size_t NumBlocks = (NumBytes+Granularity-1)/Granularity;
uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
NearBlock->size()
: 0;
// If the requested address is not aligned to the allocation granularity,
// round up to get beyond NearBlock. VirtualAlloc would have rounded down.
if (Start && Start % Granularity != 0)
Start += Granularity - Start % Granularity;
DWORD Protect = getWindowsProtectionFlags(Flags);
void *PA = ::VirtualAlloc(reinterpret_cast<void*>(Start),
NumBlocks*Granularity,
MEM_RESERVE | MEM_COMMIT, Protect);
if (PA == NULL) {
if (NearBlock) {
// Try again without the NearBlock hint
return allocateMappedMemory(NumBytes, NULL, Flags, EC);
}
EC = mapWindowsError(::GetLastError());
return MemoryBlock();
}
MemoryBlock Result;
Result.Address = PA;
Result.Size = NumBlocks*Granularity;
if (Flags & MF_EXEC)
Memory::InvalidateInstructionCache(Result.Address, Result.Size);
return Result;
}
error_code Memory::releaseMappedMemory(MemoryBlock &M) {
if (M.Address == 0 || M.Size == 0)
return error_code();
if (!VirtualFree(M.Address, 0, MEM_RELEASE))
return mapWindowsError(::GetLastError());
M.Address = 0;
M.Size = 0;
return error_code();
}
error_code Memory::protectMappedMemory(const MemoryBlock &M,
unsigned Flags) {
if (M.Address == 0 || M.Size == 0)
return error_code();
DWORD Protect = getWindowsProtectionFlags(Flags);
DWORD OldFlags;
if (!VirtualProtect(M.Address, M.Size, Protect, &OldFlags))
return mapWindowsError(::GetLastError());
if (Flags & MF_EXEC)
Memory::InvalidateInstructionCache(M.Address, M.Size);
return error_code();
}
/// InvalidateInstructionCache - Before the JIT can run a block of code
/// that has been emitted it must invalidate the instruction cache on some
/// platforms.
void Memory::InvalidateInstructionCache(
const void *Addr, size_t Len) {
FlushInstructionCache(GetCurrentProcess(), Addr, Len);
}
MemoryBlock Memory::AllocateRWX(size_t NumBytes,
const MemoryBlock *NearBlock,
std::string *ErrMsg) {
MemoryBlock MB;
error_code EC;
MB = allocateMappedMemory(NumBytes, NearBlock,
MF_READ|MF_WRITE|MF_EXEC, EC);
if (EC != error_code() && ErrMsg) {
MakeErrMsg(ErrMsg, EC.message());
}
return MB;
}
bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
error_code EC = releaseMappedMemory(M);
if (EC == error_code())
return false;
MakeErrMsg(ErrMsg, EC.message());
return true;
}
static DWORD getProtection(const void *addr) {
MEMORY_BASIC_INFORMATION info;
if (sizeof(info) == ::VirtualQuery(addr, &info, sizeof(info))) {
return info.Protect;
}
return 0;
}
bool Memory::setWritable(MemoryBlock &M, std::string *ErrMsg) {
if (!setRangeWritable(M.Address, M.Size)) {
return MakeErrMsg(ErrMsg, "Cannot set memory to writeable: ");
}
return true;
}
bool Memory::setExecutable(MemoryBlock &M, std::string *ErrMsg) {
if (!setRangeExecutable(M.Address, M.Size)) {
return MakeErrMsg(ErrMsg, "Cannot set memory to executable: ");
}
return true;
}
bool Memory::setRangeWritable(const void *Addr, size_t Size) {
DWORD prot = getProtection(Addr);
if (!prot)
return false;
if (prot == PAGE_EXECUTE || prot == PAGE_EXECUTE_READ) {
prot = PAGE_EXECUTE_READWRITE;
} else if (prot == PAGE_NOACCESS || prot == PAGE_READONLY) {
prot = PAGE_READWRITE;
}
DWORD oldProt;
Memory::InvalidateInstructionCache(Addr, Size);
return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
== TRUE;
}
bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
DWORD prot = getProtection(Addr);
if (!prot)
return false;
if (prot == PAGE_NOACCESS) {
prot = PAGE_EXECUTE;
} else if (prot == PAGE_READONLY) {
prot = PAGE_EXECUTE_READ;
} else if (prot == PAGE_READWRITE) {
prot = PAGE_EXECUTE_READWRITE;
}
DWORD oldProt;
Memory::InvalidateInstructionCache(Addr, Size);
return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
== TRUE;
}
} // namespace sys
} // namespace llvm
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