Ryujinx/ChocolArm64/Memory/MemoryManagementUnix.cs

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using Mono.Unix.Native;
using System;
namespace ChocolArm64.Memory
{
static class MemoryManagementUnix
{
public static IntPtr Allocate(ulong size)
{
ulong pageSize = (ulong)Syscall.sysconf(SysconfName._SC_PAGESIZE);
const MmapProts prot = MmapProts.PROT_READ | MmapProts.PROT_WRITE;
const MmapFlags flags = MmapFlags.MAP_PRIVATE | MmapFlags.MAP_ANONYMOUS;
IntPtr ptr = Syscall.mmap(IntPtr.Zero, size + pageSize, prot, flags, -1, 0);
if (ptr == IntPtr.Zero)
{
throw new OutOfMemoryException();
}
unsafe
{
ptr = new IntPtr(ptr.ToInt64() + (long)pageSize);
*((ulong*)ptr - 1) = size;
}
return ptr;
}
public static bool Reprotect(IntPtr address, ulong size, Memory.MemoryProtection protection)
{
MmapProts prot = GetProtection(protection);
return Syscall.mprotect(address, size, prot) == 0;
}
private static MmapProts GetProtection(Memory.MemoryProtection protection)
{
switch (protection)
{
case Memory.MemoryProtection.None: return MmapProts.PROT_NONE;
case Memory.MemoryProtection.Read: return MmapProts.PROT_READ;
case Memory.MemoryProtection.ReadAndWrite: return MmapProts.PROT_READ | MmapProts.PROT_WRITE;
case Memory.MemoryProtection.ReadAndExecute: return MmapProts.PROT_READ | MmapProts.PROT_EXEC;
case Memory.MemoryProtection.Execute: return MmapProts.PROT_EXEC;
default: throw new ArgumentException($"Invalid permission \"{protection}\".");
}
}
public static bool Free(IntPtr address)
{
ulong pageSize = (ulong)Syscall.sysconf(SysconfName._SC_PAGESIZE);
ulong size;
unsafe
{
size = *((ulong*)address - 1);
address = new IntPtr(address.ToInt64() - (long)pageSize);
}
return Syscall.munmap(address, size + pageSize) == 0;
}
}
}