windows-xp/Source/XPSP1/NT/base/ntos/rtl/ldrreloc.c

/*++

Copyright (c) 1991  Microsoft Corporation

Module Name:

   ldrreloc.c

Abstract:

    This module contains the code to relocate an image when
    the preferred base isn't available. This is called by the
    boot loader, device driver loader, and system loader.

Author:

    Mike O'Leary (mikeol) 03-Feb-1992

Revision History:

--*/

#include "ntrtlp.h"

#if 0 // These are not actually used.
      // See also ntrtl.h, RtlUshortByteSwap, RtlUlongByteSwap, RtlUlonglongByteSwap.
//
// byte swapping macros (LE/BE) used for IA64 relocations
// source != destination
//

//#define SWAP_SHORT(_dst,_src)                                                  \
//   ((((unsigned char *)_dst)[1] = ((unsigned char *)_src)[0]),                 \
//    (((unsigned char *)_dst)[0] = ((unsigned char *)_src)[1]))

//#define SWAP_INT(_dst,_src)                                                    \
//   ((((unsigned char *)_dst)[3] = ((unsigned char *)_src)[0]),                 \
//    (((unsigned char *)_dst)[2] = ((unsigned char *)_src)[1]),                 \
//    (((unsigned char *)_dst)[1] = ((unsigned char *)_src)[2]),                 \
//    (((unsigned char *)_dst)[0] = ((unsigned char *)_src)[3]))

//#define SWAP_LONG_LONG(_dst,_src)                                              \
//   ((((unsigned char *)_dst)[7] = ((unsigned char *)_src)[0]),                 \
//    (((unsigned char *)_dst)[6] = ((unsigned char *)_src)[1]),                 \
//    (((unsigned char *)_dst)[5] = ((unsigned char *)_src)[2]),                 \
//    (((unsigned char *)_dst)[4] = ((unsigned char *)_src)[3]),                 \
//    (((unsigned char *)_dst)[3] = ((unsigned char *)_src)[4]),                 \
//    (((unsigned char *)_dst)[2] = ((unsigned char *)_src)[5]),                 \
//    (((unsigned char *)_dst)[1] = ((unsigned char *)_src)[6]),                 \
//    (((unsigned char *)_dst)[0] = ((unsigned char *)_src)[7]))

#endif

//
// Mark a HIGHADJ entry as needing an increment if reprocessing.
//
#define LDRP_RELOCATION_INCREMENT   0x1

//
// Mark a HIGHADJ entry as not suitable for reprocessing.
//
#define LDRP_RELOCATION_FINAL       0x2

PIMAGE_BASE_RELOCATION
LdrProcessRelocationBlockLongLong(
    IN ULONG_PTR VA,
    IN ULONG SizeOfBlock,
    IN PUSHORT NextOffset,
    IN LONGLONG Diff
    );

#if defined(NTOS_KERNEL_RUNTIME)

#if defined(ALLOC_PRAGMA)
#pragma alloc_text(PAGE,LdrRelocateImage)
#pragma alloc_text(PAGE,LdrRelocateImageWithBias)
#pragma alloc_text(PAGE,LdrProcessRelocationBlock)
#pragma alloc_text(PAGE,LdrProcessRelocationBlockLongLong)
#endif // ALLOC_PRAGMA

#if defined(_ALPHA_)

PIMAGE_BASE_RELOCATION
LdrpProcessVolatileRelocationBlock(
    IN ULONG_PTR VA,
    IN ULONG SizeOfBlock,
    IN PUSHORT NextOffset,
    IN LONG_PTR Diff,
    IN LONG_PTR OldDiff,
    IN ULONG_PTR OldBase
    );

#if defined(ALLOC_PRAGMA)
#pragma alloc_text(INIT,LdrDoubleRelocateImage)
#pragma alloc_text(INIT,LdrpProcessVolatileRelocationBlock)
#endif // ALLOC_PRAGMA
#endif // _ALPHA_

#endif // NTOS_KERNEL_RUNTIME

#if defined(BLDR_KERNEL_RUNTIME)

typedef LDR_RELOCATE_IMAGE_RETURN_TYPE ARC_STATUS;

#else

typedef LDR_RELOCATE_IMAGE_RETURN_TYPE NTSTATUS;

#endif

LDR_RELOCATE_IMAGE_RETURN_TYPE
LdrRelocateImage (
    IN PVOID NewBase,
    IN CONST CHAR* LoaderName,
    IN LDR_RELOCATE_IMAGE_RETURN_TYPE Success,
    IN LDR_RELOCATE_IMAGE_RETURN_TYPE Conflict,
    IN LDR_RELOCATE_IMAGE_RETURN_TYPE Invalid
    )
/*++

Routine Description:

    This routine relocates an image file that was not loaded into memory
    at the preferred address.

Arguments:

    NewBase - Supplies a pointer to the image base.

    LoaderName - Indicates which loader routine is being called from.

    Success - Value to return if relocation successful.

    Conflict - Value to return if can't relocate.

    Invalid - Value to return if relocations are invalid.

Return Value:

    Success if image is relocated.
    Conflict if image can't be relocated.
    Invalid if image contains invalid fixups.

--*/

{
    //
    // Just call LdrRelocateImageWithBias() with a zero bias.
    //

    return LdrRelocateImageWithBias( NewBase,
                                     0,
                                     LoaderName,
                                     Success,
                                     Conflict,
                                     Invalid );
}


LDR_RELOCATE_IMAGE_RETURN_TYPE
LdrRelocateImageWithBias (
    IN PVOID NewBase,
    IN LONGLONG AdditionalBias,
    IN CONST CHAR* LoaderName,
    IN LDR_RELOCATE_IMAGE_RETURN_TYPE Success,
    IN LDR_RELOCATE_IMAGE_RETURN_TYPE Conflict,
    IN LDR_RELOCATE_IMAGE_RETURN_TYPE Invalid
    )
/*++

Routine Description:

    This routine relocates an image file that was not loaded into memory
    at the preferred address.

Arguments:

    NewBase - Supplies a pointer to the image base.

    AdditionalBias - An additional quantity to add to all fixups.  The
                     32-bit X86 loader uses this when loading 64-bit images
                     to specify a NewBase that is actually a 64-bit value.

    LoaderName - Indicates which loader routine is being called from.

    Success - Value to return if relocation successful.

    Conflict - Value to return if can't relocate.

    Invalid - Value to return if relocations are invalid.

Return Value:

    Success if image is relocated.
    Conflict if image can't be relocated.
    Invalid if image contains invalid fixups.

--*/

{
    LONGLONG Diff;
    ULONG TotalCountBytes = 0;
    ULONG_PTR VA;
    ULONG_PTR OldBase;
    ULONG SizeOfBlock;
    PUCHAR FixupVA;
    USHORT Offset;
    PUSHORT NextOffset = NULL;
    PIMAGE_NT_HEADERS NtHeaders;
    PIMAGE_BASE_RELOCATION NextBlock;
    LDR_RELOCATE_IMAGE_RETURN_TYPE Status;

    RTL_PAGED_CODE();

    NtHeaders = RtlImageNtHeader( NewBase );
    if ( NtHeaders ) {
        OldBase = NtHeaders->OptionalHeader.ImageBase;
        }
    else {
        Status = Invalid;
        goto Exit;
        }

    //
    // Locate the relocation section.
    //

    NextBlock = (PIMAGE_BASE_RELOCATION)RtlImageDirectoryEntryToData(
            NewBase, TRUE, IMAGE_DIRECTORY_ENTRY_BASERELOC, &TotalCountBytes);

    //
    // It is possible for a file to have no relocations, but the relocations
    // must not have been stripped.
    //

    if (!NextBlock || !TotalCountBytes) {
    
        if (NtHeaders->FileHeader.Characteristics & IMAGE_FILE_RELOCS_STRIPPED) {

#if DBG

            DbgPrint("%s: Image can't be relocated, no fixup information.\n", LoaderName);

#endif // DBG

            Status = Conflict;

        } else {
            Status = Success;
        }

        goto Exit;
    }

    //
    // If the image has a relocation table, then apply the specified fixup
    // information to the image.
    //
    Diff = (PCHAR)NewBase - (PCHAR)OldBase + AdditionalBias;
    while (TotalCountBytes) {
        SizeOfBlock = NextBlock->SizeOfBlock;
        TotalCountBytes -= SizeOfBlock;
        SizeOfBlock -= sizeof(IMAGE_BASE_RELOCATION);
        SizeOfBlock /= sizeof(USHORT);
        NextOffset = (PUSHORT)((PCHAR)NextBlock + sizeof(IMAGE_BASE_RELOCATION));

        VA = (ULONG_PTR)NewBase + NextBlock->VirtualAddress;

        if ( !(NextBlock = LdrProcessRelocationBlockLongLong( VA,
                                                              SizeOfBlock,
                                                              NextOffset,
                                                              Diff)) ) {
#if DBG
            DbgPrint("%s: Unknown base relocation type\n", LoaderName);
#endif
            Status = Invalid;
            goto Exit;
        }
    }

    Status = Success;
Exit:
    if (Status != Success) {
        DbgPrint(
            "%s: %s() failed 0x%lx\n"
            "%s: OldBase     : %p\n"
            "%s: NewBase     : %p\n"
            "%s: Diff        : 0x%I64x\n"
            "%s: NextOffset  : %p\n"
            "%s: *NextOffset : 0x%x\n"
            "%s: SizeOfBlock : 0x%lx\n",
            LoaderName, __FUNCTION__, Status,
            LoaderName, OldBase,
            LoaderName, NewBase,
            LoaderName, Diff,
            LoaderName, NextOffset,
            LoaderName, (NextOffset != NULL) ? *NextOffset : 0,
            LoaderName, SizeOfBlock
            );
#if DBG
        DbgBreakPoint();
#endif
    }
    return Status;
}

PIMAGE_BASE_RELOCATION
LdrProcessRelocationBlock(
    IN ULONG_PTR VA,
    IN ULONG SizeOfBlock,
    IN PUSHORT NextOffset,
    IN LONG_PTR Diff
    )
{
    PIMAGE_BASE_RELOCATION baseRelocation;

    baseRelocation = LdrProcessRelocationBlockLongLong( VA,
                                                        SizeOfBlock,
                                                        NextOffset,
                                                        (LONGLONG)Diff );

    return baseRelocation;
}


PIMAGE_BASE_RELOCATION
LdrProcessRelocationBlockLongLong(
    IN ULONG_PTR VA,
    IN ULONG SizeOfBlock,
    IN PUSHORT NextOffset,
    IN LONGLONG Diff
    )
{
    PUCHAR FixupVA;
    USHORT Offset;
    LONG Temp;
    LONG TempOrig;
    ULONG Temp32;
    ULONGLONG Value64;
    LONGLONG Temp64;
    LONG_PTR ActualDiff;

    RTL_PAGED_CODE();

    while (SizeOfBlock--) {

       Offset = *NextOffset & (USHORT)0xfff;
       FixupVA = (PUCHAR)(VA + Offset);

       //
       // Apply the fixups.
       //

       switch ((*NextOffset) >> 12) {

            case IMAGE_REL_BASED_HIGHLOW :
                //
                // HighLow - (32-bits) relocate the high and low half
                //      of an address.
                //
                *(LONG UNALIGNED *)FixupVA += (ULONG) Diff;
                break;

            case IMAGE_REL_BASED_HIGH :
                //
                // High - (16-bits) relocate the high half of an address.
                //
                Temp = *(PUSHORT)FixupVA << 16;
                Temp += (ULONG) Diff;
                *(PUSHORT)FixupVA = (USHORT)(Temp >> 16);
                break;

            case IMAGE_REL_BASED_HIGHADJ :
                //
                // Adjust high - (16-bits) relocate the high half of an
                //      address and adjust for sign extension of low half.
                //

#if defined(NTOS_KERNEL_RUNTIME)
                //
                // If the address has already been relocated then don't
                // process it again now or information will be lost.
                //
                if (Offset & LDRP_RELOCATION_FINAL) {
                    ++NextOffset;
                    --SizeOfBlock;
                    break;
                }
#endif

                Temp = *(PUSHORT)FixupVA << 16;
#if defined(BLDR_KERNEL_RUNTIME)
                TempOrig = Temp;
#endif
                ++NextOffset;
                --SizeOfBlock;
                Temp += (LONG)(*(PSHORT)NextOffset);
                Temp += (ULONG) Diff;
                Temp += 0x8000;
                *(PUSHORT)FixupVA = (USHORT)(Temp >> 16);

#if defined(BLDR_KERNEL_RUNTIME)
                ActualDiff = ((((ULONG_PTR)(Temp - TempOrig)) >> 16) -
                              (((ULONG_PTR)Diff) >> 16 ));

                if (ActualDiff == 1) {
                    //
                    // Mark the relocation as needing an increment if it is
                    // relocated again.
                    //
                    *(NextOffset - 1) |= LDRP_RELOCATION_INCREMENT;
                }
                else if (ActualDiff != 0) {
                    //
                    // Mark the relocation as cannot be reprocessed.
                    //
                    *(NextOffset - 1) |= LDRP_RELOCATION_FINAL;
                }
#endif

                break;

            case IMAGE_REL_BASED_LOW :
                //
                // Low - (16-bit) relocate the low half of an address.
                //
                Temp = *(PSHORT)FixupVA;
                Temp += (ULONG) Diff;
                *(PUSHORT)FixupVA = (USHORT)Temp;
                break;

            case IMAGE_REL_BASED_IA64_IMM64:

                //
                // Align it to bundle address before fixing up the
                // 64-bit immediate value of the movl instruction.
                //

                FixupVA = (PUCHAR)((ULONG_PTR)FixupVA & ~(15));
                Value64 = (ULONGLONG)0;

                //
                // Extract the lower 32 bits of IMM64 from bundle
                //


                EXT_IMM64(Value64,
                        (PULONG)FixupVA + EMARCH_ENC_I17_IMM7B_INST_WORD_X,
                        EMARCH_ENC_I17_IMM7B_SIZE_X,
                        EMARCH_ENC_I17_IMM7B_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM7B_VAL_POS_X);
                EXT_IMM64(Value64,
                        (PULONG)FixupVA + EMARCH_ENC_I17_IMM9D_INST_WORD_X,
                        EMARCH_ENC_I17_IMM9D_SIZE_X,
                        EMARCH_ENC_I17_IMM9D_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM9D_VAL_POS_X);
                EXT_IMM64(Value64,
                        (PULONG)FixupVA + EMARCH_ENC_I17_IMM5C_INST_WORD_X,
                        EMARCH_ENC_I17_IMM5C_SIZE_X,
                        EMARCH_ENC_I17_IMM5C_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM5C_VAL_POS_X);
                EXT_IMM64(Value64,
                        (PULONG)FixupVA + EMARCH_ENC_I17_IC_INST_WORD_X,
                        EMARCH_ENC_I17_IC_SIZE_X,
                        EMARCH_ENC_I17_IC_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IC_VAL_POS_X);
                EXT_IMM64(Value64,
                        (PULONG)FixupVA + EMARCH_ENC_I17_IMM41a_INST_WORD_X,
                        EMARCH_ENC_I17_IMM41a_SIZE_X,
                        EMARCH_ENC_I17_IMM41a_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM41a_VAL_POS_X);

                EXT_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM41b_INST_WORD_X),
                        EMARCH_ENC_I17_IMM41b_SIZE_X,
                        EMARCH_ENC_I17_IMM41b_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM41b_VAL_POS_X);
                EXT_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM41c_INST_WORD_X),
                        EMARCH_ENC_I17_IMM41c_SIZE_X,
                        EMARCH_ENC_I17_IMM41c_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM41c_VAL_POS_X);
                EXT_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_SIGN_INST_WORD_X),
                        EMARCH_ENC_I17_SIGN_SIZE_X,
                        EMARCH_ENC_I17_SIGN_INST_WORD_POS_X,
                        EMARCH_ENC_I17_SIGN_VAL_POS_X);
                //
                // Update 64-bit address
                //

                Value64+=Diff;

                //
                // Insert IMM64 into bundle
                //

                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM7B_INST_WORD_X),
                        EMARCH_ENC_I17_IMM7B_SIZE_X,
                        EMARCH_ENC_I17_IMM7B_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM7B_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM9D_INST_WORD_X),
                        EMARCH_ENC_I17_IMM9D_SIZE_X,
                        EMARCH_ENC_I17_IMM9D_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM9D_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM5C_INST_WORD_X),
                        EMARCH_ENC_I17_IMM5C_SIZE_X,
                        EMARCH_ENC_I17_IMM5C_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM5C_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IC_INST_WORD_X),
                        EMARCH_ENC_I17_IC_SIZE_X,
                        EMARCH_ENC_I17_IC_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IC_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM41a_INST_WORD_X),
                        EMARCH_ENC_I17_IMM41a_SIZE_X,
                        EMARCH_ENC_I17_IMM41a_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM41a_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM41b_INST_WORD_X),
                        EMARCH_ENC_I17_IMM41b_SIZE_X,
                        EMARCH_ENC_I17_IMM41b_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM41b_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_IMM41c_INST_WORD_X),
                        EMARCH_ENC_I17_IMM41c_SIZE_X,
                        EMARCH_ENC_I17_IMM41c_INST_WORD_POS_X,
                        EMARCH_ENC_I17_IMM41c_VAL_POS_X);
                INS_IMM64(Value64,
                        ((PULONG)FixupVA + EMARCH_ENC_I17_SIGN_INST_WORD_X),
                        EMARCH_ENC_I17_SIGN_SIZE_X,
                        EMARCH_ENC_I17_SIGN_INST_WORD_POS_X,
                        EMARCH_ENC_I17_SIGN_VAL_POS_X);
                break;

            case IMAGE_REL_BASED_DIR64:

                *(ULONGLONG UNALIGNED *)FixupVA += Diff;

                break;

            case IMAGE_REL_BASED_MIPS_JMPADDR :
                //
                // JumpAddress - (32-bits) relocate a MIPS jump address.
                //
                Temp = (*(PULONG)FixupVA & 0x3ffffff) << 2;
                Temp += (ULONG) Diff;
                *(PULONG)FixupVA = (*(PULONG)FixupVA & ~0x3ffffff) |
                                                ((Temp >> 2) & 0x3ffffff);

                break;

            case IMAGE_REL_BASED_ABSOLUTE :
                //
                // Absolute - no fixup required.
                //
                break;

            case IMAGE_REL_BASED_SECTION :
                //
                // Section Relative reloc.  Ignore for now.
                //
                break;

            case IMAGE_REL_BASED_REL32 :
                //
                // Relative intrasection. Ignore for now.
                //
                break;

            default :
                //
                // Illegal - illegal relocation type.
                //

                return (PIMAGE_BASE_RELOCATION)NULL;
       }
       ++NextOffset;
    }
    return (PIMAGE_BASE_RELOCATION)NextOffset;
}

#if defined(NTOS_KERNEL_RUNTIME) && defined(_ALPHA_)

NTSTATUS
LdrDoubleRelocateImage (
    IN PVOID NewBase,
    IN PVOID CurrentBase,
    IN CONST CHAR* LoaderName,
    IN NTSTATUS Success,
    IN NTSTATUS Conflict,
    IN NTSTATUS Invalid
    )

/*++

Routine Description:

    This routine handles the volatile relocations that cannot be easily repeated
    on an image file that has already been relocated at least once.

    Since this only needs to be done once (at kernel startup time), the
    decision was made to split this into a separate routine so as not to
    impact the mainline code.

    N.B. This function is for use by memory management ONLY.

Arguments:

    NewBase - Supplies a pointer to the new (second relocated) image base.

    CurrentBase - Supplies a pointer to the first relocated image base.

    LoaderName - Indicates which loader routine is being called from.

    Success - Value to return if relocation successful.

    Conflict - Value to return if can't relocate.

    Invalid - Value to return if relocations are invalid.

Return Value:

    Success if image is relocated.
    Conflict if image can't be relocated.
    Invalid if image contains invalid fixups.

--*/

{
    LONG_PTR Diff;
    LONG_PTR OldDiff;
    ULONG TotalCountBytes;
    ULONG_PTR VA;
    ULONG_PTR OldBase;
    ULONG SizeOfBlock;
    PUCHAR FixupVA;
    USHORT Offset;
    PUSHORT NextOffset;
    PIMAGE_NT_HEADERS NtHeaders;
    PIMAGE_BASE_RELOCATION NextBlock;

    RTL_PAGED_CODE();

    NtHeaders = RtlImageNtHeader( NewBase );

    OldBase = NtHeaders->OptionalHeader.ImageBase;
    OldDiff = (PCHAR)CurrentBase - (PCHAR)OldBase;

    //
    // Locate the relocation section.
    //

    NextBlock = (PIMAGE_BASE_RELOCATION)RtlImageDirectoryEntryToData(
            NewBase, TRUE, IMAGE_DIRECTORY_ENTRY_BASERELOC, &TotalCountBytes);

    if (!NextBlock || !TotalCountBytes) {

        //
        // The image does not contain a relocation table, and therefore
        // cannot be relocated.
        //
#if DBG
        DbgPrint("%s: Image can't be relocated, no fixup information.\n", LoaderName);
#endif // DBG
        return Conflict;
    }

    //
    // If the image has a relocation table, then apply the specified fixup
    // information to the image.
    //

    Diff = (PCHAR)NewBase - (PCHAR)OldBase;

    while (TotalCountBytes) {
        SizeOfBlock = NextBlock->SizeOfBlock;
        TotalCountBytes -= SizeOfBlock;
        SizeOfBlock -= sizeof(IMAGE_BASE_RELOCATION);
        SizeOfBlock /= sizeof(USHORT);
        NextOffset = (PUSHORT)((PCHAR)NextBlock + sizeof(IMAGE_BASE_RELOCATION));

        VA = (ULONG_PTR)NewBase + NextBlock->VirtualAddress;

        if ( !(NextBlock = LdrpProcessVolatileRelocationBlock(VA,SizeOfBlock,NextOffset,Diff, OldDiff, OldBase)) ) {
#if DBG
            DbgPrint("%s: Unknown base relocation type\n", LoaderName);
#endif
            return Invalid;
        }
    }

    return Success;
}

PIMAGE_BASE_RELOCATION
LdrpProcessVolatileRelocationBlock(
    IN ULONG_PTR VA,
    IN ULONG SizeOfBlock,
    IN PUSHORT NextOffset,
    IN LONG_PTR Diff,
    IN LONG_PTR OldDiff,
    IN ULONG_PTR OldBase
    )

/*++

Routine Description:

    This routine handles the volatile relocations that cannot be easily repeated
    on an image file that has already been relocated at least once.

    Since this only needs to be done once (at kernel startup time), the
    decision was made to split this into a separate routine so as not to
    impact the mainline code.

    N.B. This function is for use by memory management ONLY.

Arguments:

    TBD.

Return Value:

    Next relocation entry to process.

--*/

{
    PUCHAR FixupVA;
    USHORT Offset;
    LONG Temp;
    ULONG Temp32;
    USHORT TempShort1;
    USHORT TempShort2;
    ULONGLONG Value64;
    LONGLONG Temp64;
    USHORT RelocationType;
    IN PVOID CurrentBase;

    RTL_PAGED_CODE();

    CurrentBase = (PVOID)((ULONG_PTR)OldDiff + OldBase);

    while (SizeOfBlock--) {

       Offset = *NextOffset & (USHORT)0xfff;
       FixupVA = (PUCHAR)(VA + Offset);

       //
       // Apply the fixups.
       //

       switch ((*NextOffset) >> 12) {

            case IMAGE_REL_BASED_HIGHADJ :
                //
                // Adjust high - (16-bits) relocate the high half of an
                //      address and adjust for sign extension of low half.
                //

                //
                // Return the relocation to its original state, checking for
                // whether the entry was sign extended the 1st time it was
                // relocated.
                //
                FixupVA = (PUCHAR)((LONG_PTR)FixupVA & (LONG_PTR)~(LDRP_RELOCATION_FINAL | LDRP_RELOCATION_INCREMENT));
                Temp = *(PUSHORT)(FixupVA) << 16;

                ++NextOffset;
                --SizeOfBlock;

                // remove the carry bit from the low word
                Temp -= ((LONG)(*(PSHORT)NextOffset) + (USHORT)OldDiff + 0x8000) & ~0xFFFF;

                Temp -= (LONG)(OldDiff & ~0xffff);

                Temp += (LONG)(*(PSHORT)NextOffset);
                Temp += (ULONG) Diff;
                Temp += 0x8000;
                *(PUSHORT)FixupVA = (USHORT)(Temp >> 16);

                //
                // Mark the relocation as needing no further reprocessing.
                //
                *(NextOffset - 1) |= LDRP_RELOCATION_FINAL;
                break;

            default :
               break;
       }
       ++NextOffset;
    }
    return (PIMAGE_BASE_RELOCATION)NextOffset;
}

#endif // NTOS_KERNEL_RUNTIME && _ALPHA_