116 lines
4.4 KiB
C#
116 lines
4.4 KiB
C#
///////////////////////////////////////////////////////////////////////////////
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//
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// Microsoft Research Singularity
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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///////////////////////////////////////////////////////////////////////////////
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//
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// Simple PE Loader for Singularity
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//
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// Currently does not support:
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// x64
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// sections loaded at separate addresses
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// loading at preferred address
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// #define verbose
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// haryadi
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//#define SINGULARITY_ASMP
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namespace Microsoft.Singularity.Loader
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{
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using Microsoft.Singularity;
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using Microsoft.Singularity.Io;
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using System;
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using System.Runtime.InteropServices;
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using System.Threading;
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internal class Relocations
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{
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private const ushort sizeofBaseRelocation = 8;
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//Based relocation types.
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private const ushort IMAGE_REL_BASED_ABSOLUTE = 0;
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private const ushort IMAGE_REL_BASED_HIGH = 1;
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private const ushort IMAGE_REL_BASED_LOW = 2;
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private const ushort IMAGE_REL_BASED_HIGHLOW = 3;
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private const ushort IMAGE_REL_BASED_HIGHADJ = 4;
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internal static void FixupBlocks(IoMemory relocationMemory, int relocOffset,
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IoMemory codeMemory, uint diff)
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{
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uint va = relocationMemory.Read32Unchecked(relocOffset);
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uint size = relocationMemory.Read32Unchecked(relocOffset+4);
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while (0 != va)
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{
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#if verbose
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DebugStub.WriteLine(" FixUpBlocks: addr={0:x8}, size={1:x8}, roffset={2:x8} ",
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__arglist(va, size,relocOffset));
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#endif
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#if SINGULARITY_ASMP
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if (va == 0xffffffff || size == 0xffffffff
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||
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va >= 0xc0000000 || size >= 0xc0000000) {
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break;
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}
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#endif
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FixupBlock(relocationMemory, relocOffset,
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codeMemory, diff, va, (int)size);
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relocOffset += (int)size;
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va = relocationMemory.Read32Unchecked(relocOffset);
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size = relocationMemory.Read32Unchecked(relocOffset+4);
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}
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}
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private static void FixupBlock(IoMemory relocationMemory, int relocOffset,
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IoMemory codeMemory, uint diff, uint va, int size)
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{
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ushort fixupEntry;
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// Compute number of entries
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int numberOfEntries = (size - sizeofBaseRelocation) /2;
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#if verbose
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DebugStub.WriteLine(" FixUp: addr={0:x8}, size={1:x8}, count={2}",
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__arglist(va, size, numberOfEntries));
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#endif
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int currentSize = size - sizeofBaseRelocation;
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relocOffset += sizeofBaseRelocation; //skip block header
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for (int i = 0; i < numberOfEntries; i++)
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{
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fixupEntry = relocationMemory.Read16(relocOffset);
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relocOffset += 2;
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currentSize -= 2;
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ushort type = (ushort) (fixupEntry >>12);
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//clear out the upper bits
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uint rVA = (uint)(fixupEntry & 0xfff)+ va;
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if (IMAGE_REL_BASED_ABSOLUTE == type)
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{
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//DebugStub.WriteLine(" type={0:x4} rVA={1:x8}",
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//__arglist(type, rVA));
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// hit an alignment type. there should be no more entries
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//DebugStub.WriteLine(" fixup: count ={0}, loop count ={1} size={2}",
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//__arglist(numberOfEntries, i, currentSize));
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break;
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}
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else if (IMAGE_REL_BASED_HIGHLOW == type)
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{
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// get 32-bit word pointed by rVA
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// mem object representing loaded image is 0 based rVA is sufficient
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uint fixupItem = codeMemory.Read32Unchecked((int)rVA);
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uint newValue = unchecked(diff + (uint) fixupItem);
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#if verbose
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DebugStub.WriteLine(" Fixup: rVA={0:x8} value={1:x8} diff={2:x8}, newValue={3:x8}",
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__arglist(rVA, fixupItem, diff, newValue));
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#endif
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codeMemory.Write32Unchecked((int) rVA, newValue);
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}
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}
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//DebugStub.WriteLine();
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}
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}
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}
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