context.c

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/*++

Module Name:

    context.c

Abstract:

    This module implement the code that transfer machine state between
    context and kernel trap/exception frames.

Author:

    William K. Cheung (wcheung) 06-Mar-1998

Environment:

    Kernel mode only.

Revision History:

--*/

#include "ki.h"

VOID
RtlpFlushRSE (
    OUT PULONGLONG BackingStore,
    OUT PULONGLONG RNat
    );

#define ALIGN_NATS(Result, Source, Start, AddressOffset, Mask)    \
    if (AddressOffset == Start) {                                       \
        Result = (ULONGLONG)Source;                                     \
    } else if (AddressOffset < Start) {                                 \
        Result = (ULONGLONG)(Source << (Start - AddressOffset));        \
    } else {                                                            \
        Result = (ULONGLONG)((Source >> (AddressOffset - Start)) |      \
                             (Source << (64 + Start - AddressOffset))); \
    }                                                                   \
    Result = Result & (ULONGLONG)Mask

#define EXTRACT_NATS(Result, Source, Start, AddressOffset, Mask)        \
    Result = (ULONGLONG)(Source & (ULONGLONG)Mask);                     \
    if (AddressOffset < Start) {                                        \
        Result = Result >> (Start - AddressOffset);                     \
    } else if (AddressOffset > Start) {                                 \
        Result = ((Result << (AddressOffset - Start)) |                 \
                  (Result >> (64 + Start - AddressOffset)));            \
    }


VOID
KiGetDebugContext (
    IN PKTRAP_FRAME TrapFrame,
    IN OUT PCONTEXT ContextFrame
    )

/*++

Routine Description:

    This routine moves the user mode h/w debug registers from the debug register
    save area in the kernel stack to the context record.

Arguments:

    TrapFrame - Supplies a pointer to a trap frame from which volatile context
        should be copied into the context record.

    ContextFrame - Supplies a pointer to the context frame that receives the
        context.

Return Value:

    None.

Note:
    
    PSR.db must be set to activate the debug registers.

    This is used for getting user mode debug registers.

--*/

{
    PKDEBUG_REGISTERS DebugRegistersSaveArea;

    if (TrapFrame->PreviousMode == UserMode) {
        DebugRegistersSaveArea = GET_DEBUG_REGISTER_SAVEAREA();

        RtlCopyMemory(&ContextFrame->DbI0, 
                      (PVOID)DebugRegistersSaveArea,
                      sizeof(KDEBUG_REGISTERS));
    }
}

VOID
KiSetDebugContext (
    IN OUT PKTRAP_FRAME TrapFrame,
    IN PCONTEXT ContextFrame,
    IN KPROCESSOR_MODE PreviousMode
    )
/*++

Routine Description:

    This routine moves the debug context from the specified context frame into
    the debug registers save area in the kernel stack.

Arguments:

    TrapFrame - Supplies a pointer to a trap frame.

    ContextFrame - Supplies a pointer to a context frame that contains the
        context that is to be copied.

    PreviousMode - Supplies the processor mode for the target context.

Return Value:

    None.

Notes:

   PSR.db must be set to activate the debug registers.
   
   This is used for setting up debug registers for user mode.

--*/

{
    PKDEBUG_REGISTERS DebugRegistersSaveArea;  // User mode h/w debug registers

    if (PreviousMode == UserMode) {

        DebugRegistersSaveArea = GET_DEBUG_REGISTER_SAVEAREA();

        //
        // Sanitize the debug control regs. Leave the addresses unchanged.
        //

        DebugRegistersSaveArea->DbI0 = ContextFrame->DbI0;
        DebugRegistersSaveArea->DbI1 = SANITIZE_DR(ContextFrame->DbI1,UserMode);
        DebugRegistersSaveArea->DbI2 = ContextFrame->DbI2;
        DebugRegistersSaveArea->DbI3 = SANITIZE_DR(ContextFrame->DbI3,UserMode);
        DebugRegistersSaveArea->DbI4 = ContextFrame->DbI4;
        DebugRegistersSaveArea->DbI5 = SANITIZE_DR(ContextFrame->DbI5,UserMode);
        DebugRegistersSaveArea->DbI6 = ContextFrame->DbI6;
        DebugRegistersSaveArea->DbI7 = SANITIZE_DR(ContextFrame->DbI7,UserMode);

        DebugRegistersSaveArea->DbD0 = ContextFrame->DbD0;
        DebugRegistersSaveArea->DbD1 = SANITIZE_DR(ContextFrame->DbD1,UserMode);
        DebugRegistersSaveArea->DbD2 = ContextFrame->DbD2;
        DebugRegistersSaveArea->DbD3 = SANITIZE_DR(ContextFrame->DbD3,UserMode);
        DebugRegistersSaveArea->DbD4 = ContextFrame->DbD4;
        DebugRegistersSaveArea->DbD5 = SANITIZE_DR(ContextFrame->DbD5,UserMode);
        DebugRegistersSaveArea->DbD6 = ContextFrame->DbD6;
        DebugRegistersSaveArea->DbD7 = SANITIZE_DR(ContextFrame->DbD7,UserMode);

    }
}

VOID
KeContextFromKframes (
    IN PKTRAP_FRAME TrapFrame,
    IN PKEXCEPTION_FRAME ExceptionFrame,
    IN OUT PCONTEXT ContextFrame
    )

/*++

Routine Description:

    This routine moves the selected contents of the specified trap and exception
    frames into the specified context frame according to the specified context
    flags.

Arguments:

    TrapFrame - Supplies a pointer to a trap frame from which volatile context
        should be copied into the context record.

    ExceptionFrame - Supplies a pointer to an exception frame from which context
        should be copied into the context record.

    ContextFrame - Supplies a pointer to the context frame that receives the
        context copied from the trap and exception frames.

Return Value:

    None.

--*/

{
    ULONGLONG IntNats1, IntNats2;
    USHORT R1Offset, R4Offset;
    USHORT RNatSaveIndex;
    SHORT BsFrameSize;
    SHORT TempFrameSize;

    //
    // Set control information if specified.
    //

    if ((ContextFrame->ContextFlags & CONTEXT_CONTROL) == CONTEXT_CONTROL) {

        ContextFrame->IntGp = TrapFrame->IntGp;
        ContextFrame->IntSp = TrapFrame->IntSp;
        ContextFrame->ApUNAT = TrapFrame->ApUNAT;
        ContextFrame->BrRp = TrapFrame->BrRp;
        ContextFrame->ApCCV = TrapFrame->ApCCV;
        ContextFrame->ApDCR = TrapFrame->ApDCR;

        ContextFrame->StFPSR = TrapFrame->StFPSR;
        ContextFrame->StIPSR = TrapFrame->StIPSR;
        ContextFrame->StIIP = TrapFrame->StIIP;
        ContextFrame->StIFS = TrapFrame->StIFS;


        //
        // Set RSE control states from the trap frame.
        //

        ContextFrame->RsPFS = TrapFrame->RsPFS;

        BsFrameSize = (SHORT)(TrapFrame->StIFS & PFS_SIZE_MASK);
        RNatSaveIndex = (USHORT) (TrapFrame->RsBSP >> 3) & NAT_BITS_PER_RNAT_REG;
        TempFrameSize = BsFrameSize - RNatSaveIndex;
        while (TempFrameSize > 0) {
            BsFrameSize++;
            TempFrameSize -= NAT_BITS_PER_RNAT_REG;
        }

        ContextFrame->RsBSP = TrapFrame->RsBSP - BsFrameSize * 8;
        ContextFrame->RsBSPSTORE = ContextFrame->RsBSP;
        ContextFrame->RsRSC = TrapFrame->RsRSC;
        ContextFrame->RsRNAT = TrapFrame->RsRNAT;

#if DEBUG
        DbgPrint("KeContextFromKFrames: RsRNAT = 0x%I64x\n",
                 ContextFrame->RsRNAT);
#endif // DEBUG

        //
        // Set preserved applicaton registers from exception frame.
        //

        ContextFrame->ApLC = ExceptionFrame->ApLC;
        ContextFrame->ApEC = (ExceptionFrame->ApEC >> PFS_EC_SHIFT) & PFS_EC_MASK;

        //
        // Get iA status from the application registers
        //

        ContextFrame->StFCR = __getReg(CV_IA64_AR21);
        ContextFrame->Eflag = __getReg(CV_IA64_AR24);
        ContextFrame->SegCSD = __getReg(CV_IA64_AR25);
        ContextFrame->SegSSD = __getReg(CV_IA64_AR26);
        ContextFrame->Cflag = __getReg(CV_IA64_AR27);
        ContextFrame->StFSR = __getReg(CV_IA64_AR28);
        ContextFrame->StFIR = __getReg(CV_IA64_AR29);
        ContextFrame->StFDR = __getReg(CV_IA64_AR30);

    }

    //
    // Set integer register contents if specified.
    //

    if ((ContextFrame->ContextFlags & CONTEXT_INTEGER) == CONTEXT_INTEGER) {

        ContextFrame->IntT0 = TrapFrame->IntT0;
        ContextFrame->IntT1 = TrapFrame->IntT1;
        ContextFrame->IntT2 = TrapFrame->IntT2;
        ContextFrame->IntT3 = TrapFrame->IntT3;
        ContextFrame->IntT4 = TrapFrame->IntT4;
        ContextFrame->IntV0 = TrapFrame->IntV0;
        ContextFrame->IntTeb = TrapFrame->IntTeb;
        ContextFrame->Preds = TrapFrame->Preds;

        //
        // t5 - t22
        // 

        memcpy(&ContextFrame->IntT5, &TrapFrame->IntT5, 18*sizeof(ULONGLONG));

        //
        // Set branch registers from trap frame & exception frame
        //

        ContextFrame->BrT0 = TrapFrame->BrT0;
        ContextFrame->BrT1 = TrapFrame->BrT1;

        memcpy(&ContextFrame->BrS0, &ExceptionFrame->BrS0, 5*sizeof(ULONGLONG));

        //
        // Set integer registers s0 - s3 from exception frame.
        //

        ContextFrame->IntS0 = ExceptionFrame->IntS0;
        ContextFrame->IntS1 = ExceptionFrame->IntS1;
        ContextFrame->IntS2 = ExceptionFrame->IntS2;
        ContextFrame->IntS3 = ExceptionFrame->IntS3;

        //
        // Set the integer nats field in the context
        //

        R1Offset = (USHORT)((ULONG_PTR)(&TrapFrame->IntGp) >> 3) & 0x3f;
        R4Offset = (USHORT)((ULONG_PTR)(&ExceptionFrame->IntS0) >> 3) & 0x3f;

        ALIGN_NATS(IntNats1, TrapFrame->IntNats, 1, R1Offset, 0xFFFFFF0E);
        ALIGN_NATS(IntNats2, ExceptionFrame->IntNats, 4, R4Offset, 0xF0);
        ContextFrame->IntNats = IntNats1 | IntNats2;

#if DEBUG
        DbgPrint("KeContextFromKFrames: TF->IntNats = 0x%I64x, R1OffSet = 0x%x, R4Offset = 0x%x\n",
                 TrapFrame->IntNats, R1Offset, R4Offset);
        DbgPrint("KeContextFromKFrames: CF->IntNats = 0x%I64x, IntNats1 = 0x%I64x, IntNats2 = 0x%I64x\n",
                 ContextFrame->IntNats, IntNats1, IntNats2);
#endif // DEBUG

    }

    //
    // Set lower floating register contents if specified.
    //

    if ((ContextFrame->ContextFlags & CONTEXT_LOWER_FLOATING_POINT) == CONTEXT_LOWER_FLOATING_POINT) {

        //
        // Set EM + ia32 FP status
        //
        
        ContextFrame->StFPSR = TrapFrame->StFPSR;

        //
        // Set floating registers fs0 - fs19 from exception frame.
        //

        RtlCopyIa64FloatRegisterContext(&ContextFrame->FltS0,
                                        &ExceptionFrame->FltS0,
                                        sizeof(FLOAT128) * (4));

        RtlCopyIa64FloatRegisterContext(&ContextFrame->FltS4, 
                                        &ExceptionFrame->FltS4,
                                        16*sizeof(FLOAT128));

        //
        // Set floating registers ft0 - ft9 from trap frame.
        //

        RtlCopyIa64FloatRegisterContext(&ContextFrame->FltT0,
                                        &TrapFrame->FltT0,
                                        sizeof(FLOAT128) * (10));

    }

    if ((ContextFrame->ContextFlags & CONTEXT_HIGHER_FLOATING_POINT) == CONTEXT_HIGHER_FLOATING_POINT) {

        ContextFrame->StFPSR = TrapFrame->StFPSR;

        //
        // Set floating regs f32 - f127 from higher floating point save area
        //

        if (TrapFrame->PreviousMode == UserMode) {

            RtlCopyIa64FloatRegisterContext(
                &ContextFrame->FltF32, 
                (PFLOAT128)GET_HIGH_FLOATING_POINT_REGISTER_SAVEAREA(),
                96*sizeof(FLOAT128)
                );
        }

    }

    //
    // Get user debug registers from save area in kernel stack.
    // Note: PSR.db must be set to activate the debug registers.
    //

    if ((ContextFrame->ContextFlags & CONTEXT_DEBUG) == CONTEXT_DEBUG) {
        KiGetDebugContext(TrapFrame, ContextFrame);
    }

    return;
}

VOID
KeContextToKframes (
    IN OUT PKTRAP_FRAME TrapFrame,
    IN OUT PKEXCEPTION_FRAME ExceptionFrame,
    IN PCONTEXT ContextFrame,
    IN ULONG ContextFlags,
    IN KPROCESSOR_MODE PreviousMode
    )

/*++

Routine Description:

    This routine moves the selected contents of the specified context frame into
    the specified trap and exception frames according to the specified context
    flags.

Arguments:

    TrapFrame - Supplies a pointer to a trap frame that receives the volatile
        context from the context record.

    ExceptionFrame - Supplies a pointer to an exception frame that receives
        the nonvolatile context from the context record.

    ContextFrame - Supplies a pointer to a context frame that contains the
        context that is to be copied into the trap and exception frames.

    ContextFlags - Supplies the set of flags that specify which parts of the
        context frame are to be copied into the trap and exception frames.

    PreviousMode - Supplies the processor mode for which the trap and exception
        frames are being built.

Return Value:

    None.

--*/

{
    USHORT R1Offset, R4Offset;
    USHORT RNatSaveIndex; 
    SHORT BsFrameSize;
    SHORT TempFrameSize;

    //
    // Set control information if specified.
    //

    if ((ContextFlags & CONTEXT_CONTROL) == CONTEXT_CONTROL) {

        TrapFrame->IntGp = ContextFrame->IntGp;
        TrapFrame->IntSp = ContextFrame->IntSp;
        TrapFrame->ApUNAT = ContextFrame->ApUNAT;
        TrapFrame->BrRp = ContextFrame->BrRp;
        TrapFrame->ApCCV = ContextFrame->ApCCV;
        TrapFrame->ApDCR = SANITIZE_DCR(ContextFrame->ApDCR, PreviousMode);

        //
        // Set preserved applicaton registers in exception frame.
        //

        ExceptionFrame->ApLC = ContextFrame->ApLC;
        ExceptionFrame->ApEC &= ~(PFS_EC_MASK << PFS_EC_MASK);
        ExceptionFrame->ApEC |= ((ContextFrame->ApEC & PFS_EC_MASK) << PFS_EC_SHIFT);

        //
        // Set RSE control states in the trap frame.
        //

        TrapFrame->RsPFS = ContextFrame->RsPFS;

        BsFrameSize = (SHORT)(ContextFrame->StIFS & PFS_SIZE_MASK);
        RNatSaveIndex = (USHORT)((ContextFrame->RsBSP >> 3) & NAT_BITS_PER_RNAT_REG);

        TempFrameSize = RNatSaveIndex + BsFrameSize - NAT_BITS_PER_RNAT_REG;
        while (TempFrameSize >= 0) {
            BsFrameSize++;
            TempFrameSize -= NAT_BITS_PER_RNAT_REG;
        }

        TrapFrame->RsBSPSTORE = ContextFrame->RsBSPSTORE + BsFrameSize * 8;
        TrapFrame->RsBSP = TrapFrame->RsBSPSTORE;
        TrapFrame->RsRSC = ContextFrame->RsRSC;
        TrapFrame->RsRNAT = ContextFrame->RsRNAT;

#if DEBUG
        DbgPrint("KeContextToKFrames: RsRNAT = 0x%I64x\n", TrapFrame->RsRNAT);
#endif // DEBUG

        //
        // Set FPSR, IPSR, IIP, and IFS in the trap frame.
        //

        TrapFrame->StFPSR = SANITIZE_FSR(ContextFrame->StFPSR, PreviousMode);
        TrapFrame->StIPSR = SANITIZE_PSR(ContextFrame->StIPSR, PreviousMode);
        if (((TrapFrame->StIPSR >> PSR_RI) & 3) == 3) {
            TrapFrame->StIPSR &= ~(3i64 << PSR_RI);
        }
        TrapFrame->StIFS  = SANITIZE_IFS(ContextFrame->StIFS, PreviousMode);
        TrapFrame->StIIP  = ContextFrame->StIIP;

        //
        // DebugActive controls h/w debug registers. Set if new psr.db = 1
        //

        KeGetCurrentThread()->DebugActive = ((TrapFrame->StIPSR & (1I64 << PSR_DB)) != 0);

        //
        // Set application registers directly
        // *** TBD SANATIZE??
        //

        if (PreviousMode == UserMode ) {
            __setReg(CV_IA64_AR21, ContextFrame->StFCR);
            __setReg(CV_IA64_AR24, ContextFrame->Eflag);
            __setReg(CV_IA64_AR25, ContextFrame->SegCSD);
            __setReg(CV_IA64_AR26, ContextFrame->SegSSD);
            __setReg(CV_IA64_AR27, ContextFrame->Cflag);
            __setReg(CV_IA64_AR28, ContextFrame->StFSR);
            __setReg(CV_IA64_AR29, ContextFrame->StFIR);
            __setReg(CV_IA64_AR30, ContextFrame->StFDR);
        }
    }

    //
    // Set integer registers contents if specified.
    //

    if ((ContextFlags & CONTEXT_INTEGER) == CONTEXT_INTEGER) {

        TrapFrame->IntT0 = ContextFrame->IntT0;
        TrapFrame->IntT1 = ContextFrame->IntT1;
        TrapFrame->IntT2 = ContextFrame->IntT2;
        TrapFrame->IntT3 = ContextFrame->IntT3;
        TrapFrame->IntT4 = ContextFrame->IntT4;
        TrapFrame->IntV0 = ContextFrame->IntV0;
        TrapFrame->IntTeb = ContextFrame->IntTeb;
        TrapFrame->Preds = ContextFrame->Preds;

        //
        // t5 - t22
        //

        memcpy(&TrapFrame->IntT5, &ContextFrame->IntT5, 18*sizeof(ULONGLONG));

        //
        // Set integer registers s0 - s3 in exception frame.
        //

        ExceptionFrame->IntS0 = ContextFrame->IntS0;
        ExceptionFrame->IntS1 = ContextFrame->IntS1;
        ExceptionFrame->IntS2 = ContextFrame->IntS2;
        ExceptionFrame->IntS3 = ContextFrame->IntS3;

        //
        // Set the integer nats field in the trap & exception frames
        //

        R1Offset = (USHORT)((ULONG_PTR)(&TrapFrame->IntGp) >> 3) & 0x3f;
        R4Offset = (USHORT)((ULONG_PTR)(&ExceptionFrame->IntS0) >> 3) & 0x3f;

        EXTRACT_NATS(TrapFrame->IntNats, ContextFrame->IntNats,
                     1, R1Offset, 0xFFFFFF0E);
        EXTRACT_NATS(ExceptionFrame->IntNats, ContextFrame->IntNats,
                     4, R4Offset, 0xF0);

#if DEBUG
        DbgPrint("KeContextToKFrames: TF->IntNats = 0x%I64x, ContestFrame->IntNats = 0x%I64x, R1OffSet = 0x%x\n",
                 TrapFrame->IntNats, ContextFrame->IntNats, R1Offset);
        DbgPrint("KeContextToKFrames: EF->IntNats = 0x%I64x, R4OffSet = 0x%x\n",
                 ExceptionFrame->IntNats, R4Offset);
#endif // DEBUG

        //
        // Set other branch registers in trap and exception frames
        //

        TrapFrame->BrT0 = ContextFrame->BrT0;
        TrapFrame->BrT1 = ContextFrame->BrT1;

        memcpy(&ExceptionFrame->BrS0, &ContextFrame->BrS0, 5*sizeof(ULONGLONG));

    }

    //
    // Set lower floating register contents if specified.
    //

    if ((ContextFlags & CONTEXT_LOWER_FLOATING_POINT) == CONTEXT_LOWER_FLOATING_POINT) {

        TrapFrame->StFPSR = SANITIZE_FSR(ContextFrame->StFPSR, PreviousMode);

        //
        // Set floating registers fs0 - fs19 in exception frame.
        //

        RtlCopyIa64FloatRegisterContext(&ExceptionFrame->FltS0, 
                                        &ContextFrame->FltS0,
                                        sizeof(FLOAT128) * (4));

        RtlCopyIa64FloatRegisterContext(&ExceptionFrame->FltS4, 
                                        &ContextFrame->FltS4,
                                        16*sizeof(FLOAT128));

        //
        // Set floating registers ft0 - ft9 in trap frame.
        //

        RtlCopyIa64FloatRegisterContext(&TrapFrame->FltT0, 
                                        &ContextFrame->FltT0,
                                        sizeof(FLOAT128) * (10));

    }

    //
    // Set higher floating register contents if specified.
    //

    if ((ContextFlags & CONTEXT_HIGHER_FLOATING_POINT) == CONTEXT_HIGHER_FLOATING_POINT) {

        TrapFrame->StFPSR = SANITIZE_FSR(ContextFrame->StFPSR, PreviousMode);

        if (PreviousMode == UserMode) {

            //
            // Update the higher floating point save area (f32-f127) and 
            // set the corresponding modified bit in the PSR to 1.
            //

            RtlCopyIa64FloatRegisterContext(
                (PFLOAT128)GET_HIGH_FLOATING_POINT_REGISTER_SAVEAREA(),
                &ContextFrame->FltF32,
                96*sizeof(FLOAT128)
                );

            TrapFrame->StIPSR |= (1i64 << PSR_DFH);
        }

    }

    //
    // Set debug registers.
    //

    if ((ContextFlags & CONTEXT_DEBUG) == CONTEXT_DEBUG) {
        KiSetDebugContext (TrapFrame, ContextFrame, PreviousMode);
    }

    return;
}

VOID
KiFlushUserRseState (
    IN PKTRAP_FRAME TrapFrame
    )

/*++

Routine Description:

    This routine flushes the user rse state from the kernel backing store to the
    user backing store. The user context frame is update to reflect the new 
    context state.

Arguments:

    TrapFrame - Supplies a pointer to a trap frame.

Return Value:

    None.

--*/

{
    SHORT BsFrameSize;
    SHORT RNatSaveIndex;
    SHORT Temp;
    USHORT TearPointOffset;
    ULONGLONG TopBound, BottomBound;
    ULONGLONG UserRnats1, UserRnats2;
    ULONGLONG Mask;

    //
    // Copy user stacked registers' contents to user backing store.
    // N.B. Stack overflow could happen.
    //

    try {

        BsFrameSize = (SHORT)(TrapFrame->RsBSP - TrapFrame->RsBSPSTORE);

        if (BsFrameSize) {

            ULONGLONG Bsp, Rnat, KernelInitBsp;

            //
            // Copy the dirty stacked registers back into the
            // user backing store
            //

            RtlpFlushRSE(&Bsp, &Rnat);
            TearPointOffset = (USHORT) TrapFrame->RsBSPSTORE & 0x1F8;

            KernelInitBsp= (PCR->InitialBStore | TearPointOffset) + BsFrameSize;
            if ((KernelInitBsp | RNAT_ALIGNMENT) != (Bsp | RNAT_ALIGNMENT)) {
                Rnat = *(PULONGLONG)(KernelInitBsp | RNAT_ALIGNMENT);
            }

            RtlCopyMemory((PVOID)(TrapFrame->RsBSPSTORE),
                         (PVOID)(PCR->InitialBStore + TearPointOffset),
                         BsFrameSize);

            TopBound = TrapFrame->RsBSP | RNAT_ALIGNMENT;
            BottomBound = TrapFrame->RsBSPSTORE | RNAT_ALIGNMENT;

            RNatSaveIndex = TearPointOffset >> 3;
            Mask = (((1ULL << (NAT_BITS_PER_RNAT_REG - RNatSaveIndex)) - 1) << RNatSaveIndex);
            UserRnats1 = TrapFrame->RsRNAT & ((1ULL << RNatSaveIndex) - 1);

            if (TopBound > BottomBound) {

                //
                // user dirty stacked GR span across at least one RNAT
                // boundary; need to deposit the valid RNAT bits from
                // the trap frame into the kernel backing store.  Also,
                // the RNAT field in the trap frame has to be updated.
                //

                UserRnats2 = *(PULONGLONG)BottomBound & Mask;
                *(PULONGLONG)BottomBound = UserRnats1 | UserRnats2;
                TrapFrame->RsRNAT = Rnat;
                
#if DEBUG
                DbgPrint("KiFlushUserRseState 1: UserRnats1 = 0x%I64x, UserRnats2 = 0x%I64x, TF->RsRNAT = 0x%I64x\n",
                         UserRnats1, UserRnats2, TrapFrame->RsRNAT);
#endif // DEBUG

            } else {

                //
                // user stacked register region does not span across an
                // RNAT boundary; combine the RNAT fields from both the
                // trap frame and the context frame.
                //

                UserRnats2 = Rnat & Mask;
                TrapFrame->RsRNAT = UserRnats1 | UserRnats2;

#if DEBUG
                DbgPrint("KiFlushUserRseState 2: UserRnats1 = 0x%I64x, UserRnats2 = 0x%I64x, TF->RsRNAT = 0x%I64x\n",
                         UserRnats1, UserRnats2, TrapFrame->RsRNAT);
#endif // DEBUG

            }
        }

        //
        // Successfully copied to user backing store; set the user's
        // bspstore to the value of its own bsp.
        //

        TrapFrame->RsBSPSTORE = TrapFrame->RsBSP;

    } except (EXCEPTION_EXECUTE_HANDLER) {
        DbgPrint("WARNING: Exception raised in krnl-to-user bstore copy\n");
    }

    return;
}

VOID
KeContextToKframesSpecial (
    IN PKTHREAD Thread,
    IN OUT PKTRAP_FRAME TrapFrame,
    IN OUT PKEXCEPTION_FRAME ExceptionFrame,
    IN PCONTEXT ContextFrame,
    IN ULONG ContextFlags
    )

/*++

Routine Description:

    This routine moves the selected contents of the specified context frame into
    the specified trap and exception frames according to the specified context
    flags.

Arguments:

    TrapFrame - Supplies a pointer to a trap frame that receives the volatile
        context from the context record.

    ExceptionFrame - Supplies a pointer to an exception frame that receives
        the nonvolatile context from the context record.

    ContextFrame - Supplies a pointer to a context frame that contains the
        context that is to be copied into the trap and exception frames.

    ContextFlags - Supplies the set of flags that specify which parts of the
        context frame are to be copied into the trap and exception frames.

    PreviousMode - Supplies the processor mode for which the trap and exception
        frames are being built.

Return Value:

    None.

--*/

{
    USHORT R1Offset, R4Offset;
    USHORT RNatSaveIndex; 
    SHORT BsFrameSize;
    SHORT TempFrameSize;

    //
    // Set control information if specified.
    //

    if ((ContextFlags & CONTEXT_CONTROL) == CONTEXT_CONTROL) {

        TrapFrame->IntGp = ContextFrame->IntGp;
        TrapFrame->IntSp = ContextFrame->IntSp;
        TrapFrame->ApUNAT = ContextFrame->ApUNAT;
        TrapFrame->BrRp = ContextFrame->BrRp;
        TrapFrame->ApCCV = ContextFrame->ApCCV;
        TrapFrame->ApDCR = SANITIZE_DCR(ContextFrame->ApDCR, UserMode);

        //
        // Set preserved applicaton registers in exception frame.
        //

        ExceptionFrame->ApLC = ContextFrame->ApLC;
        ExceptionFrame->ApEC &= ~(PFS_EC_MASK << PFS_EC_MASK);
        ExceptionFrame->ApEC |= ((ContextFrame->ApEC & PFS_EC_MASK) << PFS_EC_SHIFT);

        //
        // Set RSE control states in the trap frame.
        //

        TrapFrame->RsPFS = ContextFrame->RsPFS;

        BsFrameSize = (SHORT)(ContextFrame->StIFS & PFS_SIZE_MASK);
        RNatSaveIndex = (USHORT)((ContextFrame->RsBSP >> 3) & NAT_BITS_PER_RNAT_REG);

        TempFrameSize = RNatSaveIndex + BsFrameSize - NAT_BITS_PER_RNAT_REG;
        while (TempFrameSize >= 0) {
            BsFrameSize++;
            TempFrameSize -= NAT_BITS_PER_RNAT_REG;
        }

        TrapFrame->RsBSPSTORE = ContextFrame->RsBSPSTORE + BsFrameSize * 8;
        TrapFrame->RsBSP = TrapFrame->RsBSPSTORE;
        TrapFrame->RsRSC = ContextFrame->RsRSC;
        TrapFrame->RsRNAT = ContextFrame->RsRNAT;

#if DEBUG
        DbgPrint("KeContextToKFrames: RsRNAT = 0x%I64x\n", TrapFrame->RsRNAT);
#endif // DEBUG

        //
        // Set FPSR, IPSR, IIP, and IFS in the trap frame.
        //

        TrapFrame->StFPSR = SANITIZE_FSR(ContextFrame->StFPSR, UserMode);
        TrapFrame->StIPSR = SANITIZE_PSR(ContextFrame->StIPSR, UserMode);
        if (((TrapFrame->StIPSR >> PSR_RI) & 3) == 3) {
            TrapFrame->StIPSR &= ~(3i64 << PSR_RI);
        }
        TrapFrame->StIFS  = SANITIZE_IFS(ContextFrame->StIFS, UserMode);
        TrapFrame->StIIP  = ContextFrame->StIIP;

        //
        // DebugActive controls h/w debug registers. Set if new psr.db = 1
        //

        KeGetCurrentThread()->DebugActive = ((TrapFrame->StIPSR & (1I64 << PSR_DB)) != 0);

        //
        // Set application registers directly
        //

        if (Thread == KeGetCurrentThread()) {
            __setReg(CV_IA64_AR21, ContextFrame->StFCR);
            __setReg(CV_IA64_AR24, ContextFrame->Eflag);
            __setReg(CV_IA64_AR25, ContextFrame->SegCSD);
            __setReg(CV_IA64_AR26, ContextFrame->SegSSD);
            __setReg(CV_IA64_AR27, ContextFrame->Cflag);
            __setReg(CV_IA64_AR28, ContextFrame->StFSR);
            __setReg(CV_IA64_AR29, ContextFrame->StFIR);
            __setReg(CV_IA64_AR30, ContextFrame->StFDR);
        } else {
            PKAPPLICATION_REGISTERS AppRegs;

            AppRegs = GET_APPLICATION_REGISTER_SAVEAREA(Thread->StackBase);
            AppRegs->Ar21 = ContextFrame->StFCR;
            AppRegs->Ar24 = ContextFrame->Eflag;
            AppRegs->Ar25 = ContextFrame->SegCSD;
            AppRegs->Ar26 = ContextFrame->SegSSD;
            AppRegs->Ar27 = ContextFrame->Cflag;
            AppRegs->Ar28 = ContextFrame->StFSR;
            AppRegs->Ar29 = ContextFrame->StFIR;
            AppRegs->Ar30 = ContextFrame->StFDR;
        }
    }

    //
    // Set integer registers contents if specified.
    //

    if ((ContextFlags & CONTEXT_INTEGER) == CONTEXT_INTEGER) {

        TrapFrame->IntT0 = ContextFrame->IntT0;
        TrapFrame->IntT1 = ContextFrame->IntT1;
        TrapFrame->IntT2 = ContextFrame->IntT2;
        TrapFrame->IntT3 = ContextFrame->IntT3;
        TrapFrame->IntT4 = ContextFrame->IntT4;
        TrapFrame->IntV0 = ContextFrame->IntV0;
        TrapFrame->IntTeb = ContextFrame->IntTeb;
        TrapFrame->Preds = ContextFrame->Preds;

        //
        // t5 - t22
        //

        memcpy(&TrapFrame->IntT5, &ContextFrame->IntT5, 18*sizeof(ULONGLONG));

        //
        // Set integer registers s0 - s3 in exception frame.
        //

        ExceptionFrame->IntS0 = ContextFrame->IntS0;
        ExceptionFrame->IntS1 = ContextFrame->IntS1;
        ExceptionFrame->IntS2 = ContextFrame->IntS2;
        ExceptionFrame->IntS3 = ContextFrame->IntS3;

        //
        // Set the integer nats field in the trap & exception frames
        //

        R1Offset = (USHORT)((ULONG_PTR)(&TrapFrame->IntGp) >> 3) & 0x3f;
        R4Offset = (USHORT)((ULONG_PTR)(&ExceptionFrame->IntS0) >> 3) & 0x3f;

        EXTRACT_NATS(TrapFrame->IntNats, ContextFrame->IntNats,
                     1, R1Offset, 0xFFFFFF0E);
        EXTRACT_NATS(ExceptionFrame->IntNats, ContextFrame->IntNats,
                     4, R4Offset, 0xF0);

#if DEBUG
        DbgPrint("KeContextToKFrames: TF->IntNats = 0x%I64x, ContestFrame->IntNats = 0x%I64x, R1OffSet = 0x%x\n",
                 TrapFrame->IntNats, ContextFrame->IntNats, R1Offset);
        DbgPrint("KeContextToKFrames: EF->IntNats = 0x%I64x, R4OffSet = 0x%x\n",
                 ExceptionFrame->IntNats, R4Offset);
#endif // DEBUG

        //
        // Set other branch registers in trap and exception frames
        //

        TrapFrame->BrT0 = ContextFrame->BrT0;
        TrapFrame->BrT1 = ContextFrame->BrT1;

        memcpy(&ExceptionFrame->BrS0, &ContextFrame->BrS0, 5*sizeof(ULONGLONG));

    }

    //
    // Set lower floating register contents if specified.
    //

    if ((ContextFlags & CONTEXT_LOWER_FLOATING_POINT) == CONTEXT_LOWER_FLOATING_POINT) {

        TrapFrame->StFPSR = SANITIZE_FSR(ContextFrame->StFPSR, UserMode);

        //
        // Set floating registers fs0 - fs19 in exception frame.
        //

        RtlCopyIa64FloatRegisterContext(&ExceptionFrame->FltS0, 
                                        &ContextFrame->FltS0,
                                        sizeof(FLOAT128) * (4));

        RtlCopyIa64FloatRegisterContext(&ExceptionFrame->FltS4, 
                                        &ContextFrame->FltS4,
                                        16*sizeof(FLOAT128));

        //
        // Set floating registers ft0 - ft9 in trap frame.
        //

        RtlCopyIa64FloatRegisterContext(&TrapFrame->FltT0, 
                                        &ContextFrame->FltT0,
                                        sizeof(FLOAT128) * (10));

    }

    //
    // Set higher floating register contents if specified.
    //

    if ((ContextFlags & CONTEXT_HIGHER_FLOATING_POINT) == CONTEXT_HIGHER_FLOATING_POINT) {

        TrapFrame->StFPSR = SANITIZE_FSR(ContextFrame->StFPSR, UserMode);

        //
        // Update the higher floating point save area (f32-f127) and 
        // set the corresponding modified bit in the PSR to 1.
        //

        RtlCopyIa64FloatRegisterContext(
            (PFLOAT128)GET_HIGH_FLOATING_POINT_REGISTER_SAVEAREA(),
            &ContextFrame->FltF32,
            96*sizeof(FLOAT128)
            );

        TrapFrame->StIPSR |= (1i64 << PSR_DFH);

    }

    //
    // Set debug registers.
    //

    if ((ContextFlags & CONTEXT_DEBUG) == CONTEXT_DEBUG) {
        KiSetDebugContext (TrapFrame, ContextFrame, UserMode);
    }

    return;
}

---