OpenCorePkg/Platform/OpenCore/OpenCoreKernel.c

/** @file
  OpenCore driver.

Copyright (c) 2019, vit9696. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "ProcessorBind.h"
#include <OpenCore.h>

#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/OcAppleKernelLib.h>
#include <Library/OcMiscLib.h>
#include <Library/OcStringLib.h>
#include <Library/OcVirtualFsLib.h>
#include <Library/PrintLib.h>
#include <Library/UefiBootServicesTableLib.h>

STATIC OC_STORAGE_CONTEXT  *mOcStorage;
STATIC OC_GLOBAL_CONFIG    *mOcConfiguration;
STATIC OC_CPU_INFO         *mOcCpuInfo;

STATIC
UINT32
OcParseDarwinVersion (
  IN  CONST CHAR8         *String
  )
{
  UINT32  Version;
  UINT32  VersionPart;
  UINT32  Index;
  UINT32  Index2;

  if (*String == '\0' || *String < '0' || *String > '9') {
    return 0;
  }

  Version = 0;

  for (Index = 0; Index < 3; ++Index) {
    Version *= 100;

    VersionPart = 0;

    for (Index2 = 0; Index2 < 2; ++Index2) {
      //
      // Handle single digit parts, i.e. parse 1.2.3 as 010203.
      //
      if (*String != '.' && *String != '\0') {
        VersionPart *= 10;
      }

      if (*String >= '0' && *String <= '9') {
        VersionPart += *String++ - '0';
      } else if (*String != '.' && *String != '\0') {
        return 0;
      }
    }

    Version += VersionPart;

    if (*String == '.') {
      ++String;
    }
  }

  return Version;
}

STATIC
BOOLEAN
OcMatchDarwinVersion (
  IN  UINT32  CurrentVersion,
  IN  UINT32  MinVersion,
  IN  UINT32  MaxVersion
  )
{
  //
  // Check against min <= curr <= max.
  // curr=0 -> curr=inf, max=0  -> max=inf
  //

  //
  // Replace max inf with max known version.
  //
  if (MaxVersion == 0) {
    MaxVersion = CurrentVersion;
  }

  //
  // Handle curr=inf <= max=inf(?) case.
  //
  if (CurrentVersion == 0) {
    return MaxVersion == 0;
  }

  //
  // Handle curr=num > max=num case.
  //
  if (CurrentVersion > MaxVersion) {
    return FALSE;
  }

  //
  // Handle min=num > curr=num case.
  //
  if (CurrentVersion < MinVersion) {
    return FALSE;
  }

  return TRUE;
}

STATIC
UINT32
OcKernelReadDarwinVersion (
  IN  CONST UINT8   *Kernel,
  IN  UINT32        KernelSize
  )
{
  INT32   Offset;
  UINT32  Index;
  CHAR8   DarwinVersion[32];
  UINT32  DarwinVersionInteger;


  Offset = FindPattern (
    (CONST UINT8 *) "Darwin Kernel Version ",
    NULL,
    L_STR_LEN ("Darwin Kernel Version "),
    Kernel,
    KernelSize,
    0
    );

  if (Offset < 0) {
    DEBUG ((DEBUG_WARN, "OC: Failed to determine kernel version\n"));
    return 0;
  }

  Offset += L_STR_LEN ("Darwin Kernel Version ");

  for (Index = 0; Index < ARRAY_SIZE (DarwinVersion) - 1; ++Index, ++Offset) {
    if ((UINT32) Offset >= KernelSize || Kernel[Offset] == ':') {
      break;
    }
    DarwinVersion[Index] = (CHAR8) Kernel[Offset];
  }
  DarwinVersion[Index] = '\0';
  DarwinVersionInteger = OcParseDarwinVersion (DarwinVersion);

  DEBUG ((
    DEBUG_INFO,
    "OC: Read kernel version %a (%u)\n",
    DarwinVersion,
    DarwinVersionInteger
    ));

  return DarwinVersionInteger;
}

STATIC
EFI_STATUS
OcKernelLoadKextsAndReserve (
  IN OC_STORAGE_CONTEXT  *Storage,
  IN OC_GLOBAL_CONFIG    *Config,
  OUT UINT32             *ReservedExeSize,
  OUT UINT32             *ReservedInfoSize
  )
{
  EFI_STATUS           Status;
  UINT32               Index;
  CHAR8                *BundlePath;
  CHAR8                *Comment;
  CHAR8                *PlistPath;
  CHAR8                *ExecutablePath;
  CHAR16               FullPath[OC_STORAGE_SAFE_PATH_MAX];
  OC_KERNEL_ADD_ENTRY  *Kext;

  *ReservedInfoSize = PRELINK_INFO_RESERVE_SIZE;
  *ReservedExeSize  = 0;

  for (Index = 0; Index < Config->Kernel.Add.Count; ++Index) {
    Kext = Config->Kernel.Add.Values[Index];

    if (!Kext->Enabled) {
      continue;
    }

    if (Kext->PlistDataSize == 0) {
      BundlePath     = OC_BLOB_GET (&Kext->BundlePath);
      Comment        = OC_BLOB_GET (&Kext->Comment);
      PlistPath      = OC_BLOB_GET (&Kext->PlistPath);
      if (BundlePath[0] == '\0' || PlistPath[0] == '\0') {
        DEBUG ((DEBUG_ERROR, "OC: Your config has improper for kext info\n"));
        Kext->Enabled = FALSE;
        continue;
      }

      Status = OcUnicodeSafeSPrint (
        FullPath,
        sizeof (FullPath),
        OPEN_CORE_KEXT_PATH "%a\\%a",
        BundlePath,
        PlistPath
        );
      if (EFI_ERROR (Status)) {
        DEBUG ((
          DEBUG_WARN,
          "OC: Failed to fit kext path %s%a\\%a",
          OPEN_CORE_KEXT_PATH,
          BundlePath,
          PlistPath
          ));
        Kext->Enabled = FALSE;
        continue;
      }

      UnicodeUefiSlashes (FullPath);

      Kext->PlistData = OcStorageReadFileUnicode (
        Storage,
        FullPath,
        &Kext->PlistDataSize
        );

      if (Kext->PlistData == NULL) {
        DEBUG ((
          DEBUG_ERROR,
          "OC: Plist %s is missing for kext %a (%a)\n",
          FullPath,
          BundlePath,
          Comment
          ));
        Kext->Enabled = FALSE;
        continue;
      }

      ExecutablePath = OC_BLOB_GET (&Kext->ExecutablePath);
      if (ExecutablePath[0] != '\0') {
        Status = OcUnicodeSafeSPrint (
          FullPath,
          sizeof (FullPath),
          OPEN_CORE_KEXT_PATH "%a\\%a",
          BundlePath,
          ExecutablePath
          );
        if (EFI_ERROR (Status)) {
          DEBUG ((
            DEBUG_WARN,
            "OC: Failed to fit kext path %s%a\\%a",
            OPEN_CORE_KEXT_PATH,
            BundlePath,
            ExecutablePath
            ));
          Kext->Enabled = FALSE;
          FreePool (Kext->PlistData);
          Kext->PlistData = NULL;
          continue;
        }

        UnicodeUefiSlashes (FullPath);

        Kext->ImageData = OcStorageReadFileUnicode (
          Storage,
          FullPath,
          &Kext->ImageDataSize
          );

        if (Kext->ImageData == NULL) {
          DEBUG ((
            DEBUG_ERROR,
            "OC: Image %s is missing for kext %a (%a)\n",
            FullPath,
            BundlePath,
            Comment
            ));
          Kext->Enabled = FALSE;
          FreePool (Kext->PlistData);
          Kext->PlistData = NULL;
          continue;
        }
      }
    }

    Status = PrelinkedReserveKextSize (
      ReservedInfoSize,
      ReservedExeSize,
      Kext->PlistDataSize,
      Kext->ImageData,
      Kext->ImageDataSize
      );
    if (EFI_ERROR (Status)) {
      DEBUG ((
        DEBUG_ERROR,
        "OC: Failed to fit kext %a (%a)\n",
        BundlePath,
        Comment
        ));
      Kext->Enabled = FALSE;
      FreePool (Kext->PlistData);
      Kext->PlistData = NULL;
      continue;
    }
  }

  if (*ReservedExeSize > PRELINKED_KEXTS_MAX_SIZE
   || *ReservedInfoSize + *ReservedExeSize < *ReservedExeSize) {
    return EFI_UNSUPPORTED;
  }

  DEBUG ((
    DEBUG_INFO,
    "OC: Kext reservation size info %X exe %X\n",
    *ReservedInfoSize, *ReservedExeSize
    ));
  return EFI_SUCCESS;
}

STATIC
VOID
OcKernelApplyPatches (
  IN     OC_GLOBAL_CONFIG  *Config,
  IN     UINT32            DarwinVersion,
  IN     PRELINKED_CONTEXT *Context,
  IN OUT UINT8             *Kernel,
  IN     UINT32            Size
  )
{
  EFI_STATUS             Status;
  PATCHER_CONTEXT        Patcher;
  UINT32                 Index;
  PATCHER_GENERIC_PATCH  Patch;
  OC_KERNEL_PATCH_ENTRY  *UserPatch;
  CONST CHAR8            *Target;
  CONST CHAR8            *Comment;
  UINT32                 MaxKernel;
  UINT32                 MinKernel;
  BOOLEAN                IsKernelPatch;

  IsKernelPatch = Context == NULL;

  if (IsKernelPatch) {
    ASSERT (Kernel != NULL);

    Status = PatcherInitContextFromBuffer (
      &Patcher,
      Kernel,
      Size
      );

    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_ERROR, "OC: Kernel patcher kernel init failure - %r\n", Status));
      return;
    }
  }

  for (Index = 0; Index < Config->Kernel.Patch.Count; ++Index) {
    UserPatch = Config->Kernel.Patch.Values[Index];
    Target    = OC_BLOB_GET (&UserPatch->Identifier);
    Comment   = OC_BLOB_GET (&UserPatch->Comment);

    if (!UserPatch->Enabled || (AsciiStrCmp (Target, "kernel") == 0) != IsKernelPatch) {
      continue;
    }

    MaxKernel   = OcParseDarwinVersion (OC_BLOB_GET (&UserPatch->MaxKernel));
    MinKernel   = OcParseDarwinVersion (OC_BLOB_GET (&UserPatch->MinKernel));

    if (!OcMatchDarwinVersion (DarwinVersion, MinKernel, MaxKernel)) {
      DEBUG ((
        DEBUG_INFO,
        "OC: Kernel patcher skips %a (%a) patch at %u due to version %u <= %u <= %u\n",
        Target,
        Comment,
        Index,
        MinKernel,
        DarwinVersion,
        MaxKernel
        ));
      continue;
    }

    if (!IsKernelPatch) {
      Status = PatcherInitContextFromPrelinked (
        &Patcher,
        Context,
        Target
        );

      if (EFI_ERROR (Status)) {
        DEBUG ((DEBUG_WARN, "OC: Kernel patcher %a (%a) init failure - %r\n", Target, Comment, Status));
        continue;
      } else {
        DEBUG ((DEBUG_INFO, "OC: Kernel patcher %a (%a) init succeed\n", Target, Comment));
      }
    }

    //
    // Ignore patch if:
    // - There is nothing to replace.
    // - We have neither symbolic base, nor find data.
    // - Find and replace mismatch in size.
    // - Mask and ReplaceMask mismatch in size when are available.
    //
    if (UserPatch->Replace.Size == 0
      || (OC_BLOB_GET (&UserPatch->Base)[0] == '\0' && UserPatch->Find.Size != UserPatch->Replace.Size)
      || (UserPatch->Mask.Size > 0 && UserPatch->Find.Size != UserPatch->Mask.Size)
      || (UserPatch->ReplaceMask.Size > 0 && UserPatch->Find.Size != UserPatch->ReplaceMask.Size)) {
      DEBUG ((DEBUG_ERROR, "OC: Kernel patch %u for %a (%a) is borked\n", Index, Target, Comment));
      continue;
    }

    ZeroMem (&Patch, sizeof (Patch));

    if (OC_BLOB_GET (&UserPatch->Comment)[0] != '\0') {
      Patch.Comment  = OC_BLOB_GET (&UserPatch->Comment);
    }

    if (OC_BLOB_GET (&UserPatch->Base)[0] != '\0') {
      Patch.Base  = OC_BLOB_GET (&UserPatch->Base);
    }

    if (UserPatch->Find.Size > 0) {
      Patch.Find  = OC_BLOB_GET (&UserPatch->Find);
    }

    Patch.Replace = OC_BLOB_GET (&UserPatch->Replace);

    if (UserPatch->Mask.Size > 0) {
      Patch.Mask  = OC_BLOB_GET (&UserPatch->Mask);
    }

    if (UserPatch->ReplaceMask.Size > 0) {
      Patch.ReplaceMask = OC_BLOB_GET (&UserPatch->ReplaceMask);
    }

    Patch.Size    = UserPatch->Replace.Size;
    Patch.Count   = UserPatch->Count;
    Patch.Skip    = UserPatch->Skip;
    Patch.Limit   = UserPatch->Limit;

    Status = PatcherApplyGenericPatch (&Patcher, &Patch);
    DEBUG ((
      EFI_ERROR (Status) ? DEBUG_WARN : DEBUG_INFO,
      "OC: Kernel patcher result %u for %a (%a) - %r\n",
      Index,
      Target,
      Comment,
      Status
      ));
  }

  if (!IsKernelPatch) {
    if (Config->Kernel.Quirks.AppleCpuPmCfgLock) {
      PatchAppleCpuPmCfgLock (Context);
    }

    if (Config->Kernel.Quirks.ExternalDiskIcons) {
      PatchForceInternalDiskIcons (Context);
    }

    if (Config->Kernel.Quirks.ThirdPartyDrives) {
      PatchThirdPartyDriveSupport (Context);
    }

    if (Config->Kernel.Quirks.XhciPortLimit) {
      PatchUsbXhciPortLimit (Context);
    }

    if (Config->Kernel.Quirks.DisableIoMapper) {
      PatchAppleIoMapperSupport (Context);
    }

    if (Config->Kernel.Quirks.DisableRtcChecksum) {
      PatchAppleRtcChecksum (Context);
    }

    if (Config->Kernel.Quirks.IncreasePciBarSize) {
      PatchIncreasePciBarSize (Context);     
    }

    if (Config->Kernel.Quirks.CustomSmbiosGuid) {
      PatchCustomSmbiosGuid (Context);
    }

    if (Config->Kernel.Quirks.DummyPowerManagement) {
      PatchDummyPowerManagement (Context);
    }
  } else {
    if (Config->Kernel.Quirks.AppleXcpmCfgLock) {
      PatchAppleXcpmCfgLock (&Patcher);
    }

    if (Config->Kernel.Quirks.AppleXcpmExtraMsrs) {
      PatchAppleXcpmExtraMsrs (&Patcher);
    }

    if (Config->Kernel.Quirks.AppleXcpmForceBoost) {
      PatchAppleXcpmForceBoost (&Patcher);
    }

    if (Config->Kernel.Quirks.PanicNoKextDump) {
      PatchPanicKextDump (&Patcher);
    }

    if (Config->Kernel.Emulate.Cpuid1Data[0] != 0
      || Config->Kernel.Emulate.Cpuid1Data[1] != 0
      || Config->Kernel.Emulate.Cpuid1Data[2] != 0
      || Config->Kernel.Emulate.Cpuid1Data[3] != 0) {
      PatchKernelCpuId (
        &Patcher,
        mOcCpuInfo,
        Config->Kernel.Emulate.Cpuid1Data,
        Config->Kernel.Emulate.Cpuid1Mask
        );
    }

    if (Config->Kernel.Quirks.LapicKernelPanic) {
      PatchLapicKernelPanic (&Patcher);
    }

    if (Config->Kernel.Quirks.PowerTimeoutKernelPanic) {
      PatchPowerStateTimeout (&Patcher);
    }
  }
}

STATIC
VOID
OcKernelBlockKexts (
  IN     OC_GLOBAL_CONFIG  *Config,
  IN     UINT32            DarwinVersion,
  IN     PRELINKED_CONTEXT *Context
  )
{
  EFI_STATUS             Status;
  PATCHER_CONTEXT        Patcher;
  UINT32                 Index;
  OC_KERNEL_BLOCK_ENTRY  *Kext;
  CONST CHAR8            *Target;
  CONST CHAR8            *Comment;
  UINT32                 MaxKernel;
  UINT32                 MinKernel;

  for (Index = 0; Index < Config->Kernel.Block.Count; ++Index) {
    Kext    = Config->Kernel.Block.Values[Index];
    Target  = OC_BLOB_GET (&Kext->Identifier);
    Comment = OC_BLOB_GET (&Kext->Comment);

    if (!Kext->Enabled) {
      continue;
    }

    MaxKernel = OcParseDarwinVersion (OC_BLOB_GET (&Kext->MaxKernel));
    MinKernel = OcParseDarwinVersion (OC_BLOB_GET (&Kext->MinKernel));

    if (!OcMatchDarwinVersion (DarwinVersion, MinKernel, MaxKernel)) {
      DEBUG ((
        DEBUG_INFO,
        "OC: Prelink blocker skips %a (%a) block at %u due to version %u <= %u <= %u\n",
        Target,
        Comment,
        Index,
        MinKernel,
        DarwinVersion,
        MaxKernel
        ));
      continue;
    }

    Status = PatcherInitContextFromPrelinked (
      &Patcher,
      Context,
      Target
      );

    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_WARN, "OC: Prelink blocker %a (%a) init failure - %r\n", Target, Comment, Status));
      continue;
    }

    Status = PatcherBlockKext (&Patcher);

    DEBUG ((
      EFI_ERROR (Status) ? DEBUG_WARN : DEBUG_INFO,
      "OC: Prelink blocker %a (%a) - %r\n",
      Target,
      Comment,
      Status
      ));
  }
}

STATIC
EFI_STATUS
OcKernelProcessPrelinked (
  IN     OC_GLOBAL_CONFIG  *Config,
  IN     UINT32            DarwinVersion,
  IN OUT UINT8             *Kernel,
  IN     UINT32            *KernelSize,
  IN     UINT32            AllocatedSize,
  IN     UINT32            LinkedExpansion,
  IN     UINT32            ReservedExeSize
  )
{
  EFI_STATUS           Status;
  PRELINKED_CONTEXT    Context;
  CHAR8                *BundlePath;
  CHAR8                *ExecutablePath;
  CHAR8                *Comment;
  UINT32               Index;
  CHAR8                FullPath[OC_STORAGE_SAFE_PATH_MAX];
  OC_KERNEL_ADD_ENTRY  *Kext;
  UINT32               MaxKernel;
  UINT32               MinKernel;

  Status = PrelinkedContextInit (&Context, Kernel, *KernelSize, AllocatedSize);

  if (!EFI_ERROR (Status)) {
    OcKernelApplyPatches (Config, DarwinVersion, &Context, NULL, 0);

    OcKernelBlockKexts (Config, DarwinVersion, &Context);

    Status = PrelinkedInjectPrepare (
      &Context,
      LinkedExpansion,
      ReservedExeSize
      );
    if (!EFI_ERROR (Status)) {
      for (Index = 0; Index < Config->Kernel.Add.Count; ++Index) {
        Kext = Config->Kernel.Add.Values[Index];

        if (!Kext->Enabled || Kext->PlistDataSize == 0) {
          continue;
        }

        BundlePath  = OC_BLOB_GET (&Kext->BundlePath);
        Comment     = OC_BLOB_GET (&Kext->Comment);
        MaxKernel   = OcParseDarwinVersion (OC_BLOB_GET (&Kext->MaxKernel));
        MinKernel   = OcParseDarwinVersion (OC_BLOB_GET (&Kext->MinKernel));

        if (!OcMatchDarwinVersion (DarwinVersion, MinKernel, MaxKernel)) {
          DEBUG ((
            DEBUG_INFO,
            "OC: Prelink injection skips %a (%a) kext at %u due to version %u <= %u <= %u\n",
            BundlePath,
            Comment,
            Index,
            MinKernel,
            DarwinVersion,
            MaxKernel
            ));
          continue;
        }

        Status = OcAsciiSafeSPrint (FullPath, sizeof (FullPath), "/Library/Extensions/%a", BundlePath);
        if (EFI_ERROR (Status)) {
          DEBUG ((DEBUG_WARN, "OC: Failed to fit kext path /Library/Extensions/%a", BundlePath));
          continue;
        }

        if (Kext->ImageData != NULL) {
          ExecutablePath = OC_BLOB_GET (&Kext->ExecutablePath);
        } else {
          ExecutablePath = NULL;
        }

        Status = PrelinkedInjectKext (
          &Context,
          FullPath,
          Kext->PlistData,
          Kext->PlistDataSize,
          ExecutablePath,
          Kext->ImageData,
          Kext->ImageDataSize
          );

        DEBUG ((
          EFI_ERROR (Status) ? DEBUG_WARN : DEBUG_INFO,
          "OC: Prelink injection %a (%a) - %r\n",
          BundlePath,
          Comment,
          Status
          ));
      }

      DEBUG ((
        DEBUG_INFO,
        "OC: Prelink size %u kext offset %u reserved %u\n",
        Context.PrelinkedSize,
        Context.KextsFileOffset,
        ReservedExeSize
        ));

      ASSERT (Context.PrelinkedSize - Context.KextsFileOffset <= ReservedExeSize);

      Status = PrelinkedInjectComplete (&Context);
      if (EFI_ERROR (Status)) {
        DEBUG ((DEBUG_WARN, "OC: Prelink insertion error - %r\n", Status));
      }
    } else {
      DEBUG ((DEBUG_WARN, "OC: Prelink inject prepare error - %r\n", Status));
    }

    *KernelSize = Context.PrelinkedSize;

    PrelinkedContextFree (&Context);
  }

  return Status;
}

STATIC
EFI_STATUS
EFIAPI
OcKernelFileOpen (
  IN  EFI_FILE_PROTOCOL       *This,
  OUT EFI_FILE_PROTOCOL       **NewHandle,
  IN  CHAR16                  *FileName,
  IN  UINT64                  OpenMode,
  IN  UINT64                  Attributes
  )
{
  EFI_STATUS         Status;
  BOOLEAN            Result;
  UINT8              *Kernel;
  UINT32             KernelSize;
  UINT32             AllocatedSize;
  CHAR16             *FileNameCopy;
  EFI_FILE_PROTOCOL  *VirtualFileHandle;
  EFI_STATUS         PrelinkedStatus;
  EFI_TIME           ModificationTime;
  UINT32             DarwinVersion;
  UINT32             ReservedInfoSize;
  UINT32             ReservedExeSize;
  UINT32             LinkedExpansion;
  UINT32             ReservedFullSize;

  Status = SafeFileOpen (This, NewHandle, FileName, OpenMode, Attributes);

  DEBUG ((
    DEBUG_VERBOSE,
    "OC: Opening file %s with %u mode gave - %r\n",
    FileName,
    (UINT32) OpenMode,
    Status
    ));

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // boot.efi uses /S/L/K/kernel as is to determine valid filesystem.
  // Just skip it to speedup the boot process.
  // On 10.9 mach_kernel is loaded for manual linking aferwards, so we cannot skip it.
  //
  if (OpenMode == EFI_FILE_MODE_READ
    && OcStriStr (FileName, L"kernel") != NULL
    && StrCmp (FileName, L"System\\Library\\Kernels\\kernel") != 0) {

    OcKernelLoadKextsAndReserve (
      mOcStorage,
      mOcConfiguration,
      &ReservedExeSize,
      &ReservedInfoSize
      );

    LinkedExpansion = KcGetSegmentFixupChainsSize (ReservedExeSize);
    if (LinkedExpansion == 0) {
      return EFI_UNSUPPORTED;
    }

    Result = OcOverflowTriAddU32 (
      ReservedInfoSize,
      ReservedExeSize,
      LinkedExpansion,
      &ReservedFullSize
      );
    if (Result) {
      return EFI_UNSUPPORTED;
    }

    DEBUG ((DEBUG_INFO, "OC: Trying XNU hook on %s\n", FileName));
    Status = ReadAppleKernel (
      *NewHandle,
      &Kernel,
      &KernelSize,
      &AllocatedSize,
      ReservedFullSize
      );
    DEBUG ((DEBUG_INFO, "OC: Result of XNU hook on %s is %r\n", FileName, Status));

    if (!EFI_ERROR (Status)) {
      DarwinVersion = OcKernelReadDarwinVersion (Kernel, KernelSize);
      OcKernelApplyPatches (mOcConfiguration, DarwinVersion, NULL, Kernel, KernelSize);

      PrelinkedStatus = OcKernelProcessPrelinked (
        mOcConfiguration,
        DarwinVersion,
        Kernel,
        &KernelSize,
        AllocatedSize,
        LinkedExpansion,
        ReservedExeSize
        );

      DEBUG ((DEBUG_INFO, "OC: Prelinked status - %r\n", PrelinkedStatus));

      Status = GetFileModificationTime (*NewHandle, &ModificationTime);
      if (EFI_ERROR (Status)) {
        ZeroMem (&ModificationTime, sizeof (ModificationTime));
      }

      (*NewHandle)->Close(*NewHandle);

      //
      // This was our file, yet firmware is dying.
      //
      FileNameCopy = AllocateCopyPool (StrSize (FileName), FileName);
      if (FileNameCopy == NULL) {
        DEBUG ((DEBUG_WARN, "OC: Failed to allocate kernel name (%a) copy\n", FileName));
        FreePool (Kernel);
        return EFI_OUT_OF_RESOURCES;
      }

      Status = CreateVirtualFile (FileNameCopy, Kernel, KernelSize, &ModificationTime, &VirtualFileHandle);
      if (EFI_ERROR (Status)) {
        DEBUG ((DEBUG_WARN, "OC: Failed to virtualise kernel file (%a)\n", FileName));
        FreePool (Kernel);
        FreePool (FileNameCopy);
        return EFI_OUT_OF_RESOURCES;
      }

      //
      // Return our handle.
      //
      *NewHandle = VirtualFileHandle;
      return EFI_SUCCESS;
    }
  }

  //
  // This is not Apple kernel, just return the original file.
  // We recurse the filtering to additionally catch com.apple.boot.[RPS] directories.
  //
  return CreateRealFile (*NewHandle, OcKernelFileOpen, TRUE, NewHandle);
}

VOID
OcLoadKernelSupport (
  IN OC_STORAGE_CONTEXT  *Storage,
  IN OC_GLOBAL_CONFIG    *Config,
  IN OC_CPU_INFO         *CpuInfo
  )
{
  EFI_STATUS  Status;

  Status = EnableVirtualFs (gBS, OcKernelFileOpen);

  if (!EFI_ERROR (Status)) {
    mOcStorage       = Storage;
    mOcConfiguration = Config;
    mOcCpuInfo       = CpuInfo;
  } else {
    DEBUG ((DEBUG_ERROR, "OC: Failed to enable vfs - %r\n", Status));
  }
}

VOID
OcUnloadKernelSupport (
  VOID
  )
{
  EFI_STATUS  Status;

  if (mOcStorage != NULL) {
    Status = DisableVirtualFs (gBS);
    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_ERROR, "OC: Failed to disable vfs - %r\n", Status));
    }
    mOcStorage       = NULL;
    mOcConfiguration = NULL;
  }
}