/*++

Copyright (c) 1989  Microsoft Corporation
Copyright (c) 1993  IBM Corporation

Module Name:

   debugsup.c

Abstract:

    This module contains routines which provide support for the
    kernel debugger.

Author:

    Lou Perazzoli (loup) 02-Aug-90

    Modified for PowerPC by Mark Mergen (mergen@watson.ibm.com) 6-Oct-93

Revision History:

--*/

#include "mi.h"

PVOID
MmDbgReadCheck (
    IN PVOID VirtualAddress
    )

/*++

Routine Description:

    PowerPC implementation specific:

    This routine returns the virtual address which is valid (mapped)
    for read access.

    The address may be within the PowerPC kernel BAT or may be
    otherwise valid and readable.

Arguments:

    VirtualAddress - Supplies the virtual address to check.

Return Value:

    Returns NULL if the address is not valid or readable, otherwise
    returns the virtual address.

Environment:

    Kernel mode IRQL at DISPATCH_LEVEL or greater.

--*/

{
    if ((VirtualAddress >= (PVOID)KSEG0_BASE) &&
        (VirtualAddress < (PVOID)KSEG2_BASE)) {
        return VirtualAddress;
    }

    if ((VirtualAddress >= (PVOID)KIPCR) &&
            (VirtualAddress < (PVOID)(KIPCR2 + PAGE_SIZE))) {
        return VirtualAddress;
    }

    if (!MmIsAddressValid (VirtualAddress)) {
        return NULL;
    }

    return VirtualAddress;
}

PVOID
MmDbgWriteCheck (
    IN PVOID VirtualAddress
    )

/*++

Routine Description:

    PowerPC implementation specific:

    This routine returns the virtual address which is valid (mapped)
    for write access.

    The address may be within the PowerPC kernel BAT or may be
    otherwise valid and writable.

Arguments:

    VirtualAddress - Supplies the virtual address to check.

Return Value:

    Returns NULL if the address is not valid or writable, otherwise
    returns the virtual address.

Environment:

    Kernel mode IRQL at DISPATCH_LEVEL or greater.

--*/

{
    PMMPTE PointerPte;

    if ((VirtualAddress >= (PVOID)KSEG0_BASE) &&
        (VirtualAddress < (PVOID)KSEG2_BASE)) {
        return VirtualAddress;
    }

    if ((VirtualAddress >= (PVOID)KIPCR) &&
        (VirtualAddress < (PVOID)(KIPCR2 + PAGE_SIZE))) {
        return VirtualAddress;
    }

    if (!MmIsAddressValid (VirtualAddress)) {
        return NULL;
    }

    //
    // This is being added back in permanently since the PowerPC
    // hardware debug registers break in before the instruction
    // is executed. This will generally allow the kernel debugger
    // to step over the instruction that triggered the hardware
    // debug register breakpoint.
    //

    if (VirtualAddress <= MM_HIGHEST_USER_ADDRESS) {

        // This code is similar in spirit to that in the MIPS version.
        // It returns a writable alias for breakpoints in user pages.
        // However, it uses the virtual address reserved for the debugger,
        // rather than the wired-in KSEG0 translation available in MIPS.
        //
        // N.B. Microsoft says kernel debugger can't do user code at all.

        return MmDbgTranslatePhysicalAddress (
                   MmGetPhysicalAddress (VirtualAddress) );
    }

    PointerPte = MiGetPteAddress (VirtualAddress);
    if (PointerPte->u.Hard.Write == 0) {
        return NULL;
    }

    return VirtualAddress;
}

PVOID
MmDbgTranslatePhysicalAddress (
    IN PHYSICAL_ADDRESS PhysicalAddress
    )

/*++

Routine Description:

    PowerPC implementation specific:

    This routine maps the specified physical address and returns
    the virtual address which maps the physical address.

    The next call to MmDbgTranslatePhyiscalAddress removes the
    previous phyiscal address translation, hence on a single
    physical address can be examined at a time (can't cross page
    boundaries).

Arguments:

    PhysicalAddress - Supplies the phyiscal address to map and translate.

Return Value:

    The virtual address which corresponds to the phyiscal address.

Environment:

    Kernel mode IRQL at DISPATCH_LEVEL or greater.

--*/

{
    PVOID BaseAddress;

    BaseAddress = MiGetVirtualAddressMappedByPte (MmDebugPte);

    KiFlushSingleTb (TRUE, BaseAddress);

    *MmDebugPte = ValidKernelPte;
    MmDebugPte->u.Hard.PageFrameNumber = PhysicalAddress.LowPart >> PAGE_SHIFT;

    return (PVOID)((ULONG)BaseAddress + BYTE_OFFSET(PhysicalAddress.LowPart));
}