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Support opening the INI1 from a v17.0.0+ kernel

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Alex Barney 2023-10-17 21:57:15 -07:00
parent c03e4d3f71
commit ae9ea9b7f6
1 changed files with 62 additions and 31 deletions
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93
src/LibHac/Kernel/IniExtract.cs
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@ -26,42 +26,73 @@ public static class IniExtract
uint kernelSize = (uint)kernelSizeLong;
using (var array = new RentedArray<byte>(0x1000 + Unsafe.SizeOf<KernelMap>()))
{
// The kernel map should be in the first 0x1000 bytes
if (kernelStorage.Read(0, array.Span).IsFailure())
return false;
ref byte start = ref array.Span[0];
// Search every 4 bytes for a valid kernel map
for (int i = 0; i < 0x1000; i += sizeof(int))
{
ref KernelMap map = ref Unsafe.As<byte, KernelMap>(ref Unsafe.Add(ref start, i));
if (IsValidKernelMap(in map, kernelSize))
{
// Verify the ini header at the offset in the found map
var header = new InitialProcessBinaryReader.IniHeader();
if (kernelStorage.Read(map.Ini1StartOffset, SpanHelpers.AsByteSpan(ref header)).IsFailure())
return false;
if (header.Magic != InitialProcessBinaryReader.ExpectedMagic)
return false;
offset = (int)map.Ini1StartOffset;
size = header.Size;
return true;
}
}
// .crt0 is located at the start of the kernel pre-17.0.0
// 17.0.0+ kernels start with a "b crt0" branch instruction followed by 0x7FC of zeros
// The kernel map in this case will contain offsets relative to itself rather than to the start of the kernel
int crt0Offset = 0;
bool isMapAddressRelativeToItself = false;
// Check if the first 4 bytes of the kernel is a branch instruction, and get the target if it is
ulong inst = 0;
if (kernelStorage.Read(0, SpanHelpers.AsByteSpan(ref inst)).IsFailure())
return false;
if ((inst & 0xFFFFFFFFFF000000) == 0x0000000014000000)
{
crt0Offset = (int)((inst & 0x00FFFFFF) << 2);
isMapAddressRelativeToItself = true;
}
using var array = new RentedArray<byte>(0x1000 + Unsafe.SizeOf<KernelMap>());
if (kernelStorage.Read(crt0Offset, array.Span).IsFailure())
return false;
ref byte start = ref MemoryMarshal.GetReference(array.Span);
// Search every 4 bytes for a valid kernel map
for (int i = 0; i < 0x1000 - Unsafe.SizeOf<KernelMap>(); i += sizeof(int))
{
ref KernelMap map = ref Unsafe.As<byte, KernelMap>(ref Unsafe.Add(ref start, i));
uint mapOffsetAdjustment = isMapAddressRelativeToItself ? (uint)(crt0Offset + i) : 0;
if (IsValidKernelMap(in map, kernelSize, mapOffsetAdjustment))
{
// Verify the ini header at the offset in the found map
var header = new InitialProcessBinaryReader.IniHeader();
if (kernelStorage.Read(map.Ini1StartOffset + mapOffsetAdjustment, SpanHelpers.AsByteSpan(ref header)).IsFailure())
return false;
if (header.Magic != InitialProcessBinaryReader.ExpectedMagic)
continue;
offset = (int)(map.Ini1StartOffset + mapOffsetAdjustment);
size = header.Size;
return true;
}
}
return false;
}
private static bool IsValidKernelMap(in KernelMap map, uint maxSize)
private static bool IsValidKernelMap(in KernelMap rawMap, uint maxSize, uint adj)
{
KernelMap adjustedMap = rawMap;
adjustedMap.TextStartOffset += adj;
adjustedMap.TextEndOffset += adj;
adjustedMap.RodataStartOffset += adj;
adjustedMap.RodataEndOffset += adj;
adjustedMap.DataStartOffset += adj;
adjustedMap.DataEndOffset += adj;
adjustedMap.BssStartOffset += adj;
adjustedMap.BssEndOffset += adj;
adjustedMap.Ini1StartOffset += adj;
adjustedMap.DynamicOffset += adj;
adjustedMap.InitArrayStartOffset += adj;
adjustedMap.InitArrayStartOffset += adj;
ref KernelMap map = ref adjustedMap;
if (map.TextStartOffset != 0) return false;
if (map.TextStartOffset >= map.TextEndOffset) return false;
if ((map.TextEndOffset & 0xFFF) != 0) return false;