wrmsr.cpp File Reference

wrmsr command More...

#include "pch.h"

Functions
VOID	CommandWrmsrHelp ()
	help of the wrmsr command
VOID	CommandWrmsr (vector< CommandToken > CommandTokens, string Command)
	wrmsr command handler

Variables
BOOLEAN	g_IsKdModuleLoaded
	shows whether the kernel debugger (KD) module is loaded or not

Detailed Description

wrmsr command

Author

Sina Karvandi (sina@.nosp@m.hype.nosp@m.rdbg..nosp@m.org)

Version

0.1

Date

2020-05-27

Copyright

This project is released under the GNU Public License v3.

Function Documentation

CommandWrmsr()

VOID CommandWrmsr	(	vector< CommandToken >	CommandTokens,
		string	Command )

wrmsr command handler

Parameters

CommandTokens
Command

Returns

VOID

{
    BOOL                           Status;
    UINT64                         Msr;
    ULONG                          ReturnedLength;
    DEBUGGER_READ_AND_WRITE_ON_MSR MsrWriteRequest = {0};
    BOOL                           IsNextCoreId    = FALSE;
    BOOL                           SetMsr          = FALSE;
    BOOL                           SetValue        = FALSE;
    UINT64                         Value           = 0;
    UINT32                         CoreNumer       = DEBUGGER_READ_AND_WRITE_ON_MSR_APPLY_ALL_CORES;
    BOOLEAN                        IsFirstCommand  = TRUE;
 
    if (CommandTokens.size() >= 6)
    {
        ShowMessages("incorrect use of the '%s'\n\n",
                     GetCaseSensitiveStringFromCommandToken(CommandTokens.at(0)).c_str());
        CommandWrmsrHelp();
        return;
    }
 
    for (auto Section : CommandTokens)
    {
        if (IsFirstCommand == TRUE)
        {
            IsFirstCommand = FALSE;
            continue;
        }
 
        if (IsNextCoreId)
        {
            if (!ConvertTokenToUInt32(Section, &CoreNumer))
            {
                ShowMessages("please specify a correct hex value for core id\n\n");
                CommandWrmsrHelp();
                return;
            }
 
            IsNextCoreId = FALSE;
            continue;
        }
 
        if (CompareLowerCaseStrings(Section, "core"))
        {
            IsNextCoreId = TRUE;
            continue;
        }
 
        if (!SetMsr)
        {
            if (!ConvertTokenToUInt64(Section, &Msr))
            {
                ShowMessages("please specify a correct hex value to be read\n\n");
                CommandWrmsrHelp();
                return;
            }
            else
            {
                //
                // Means that the MSR is set, next we should read value
                //
                SetMsr = TRUE;
                continue;
            }
        }
 
        if (SetMsr)
        {
            if (!SymbolConvertNameOrExprToAddress(GetCaseSensitiveStringFromCommandToken(Section), &Value))
            {
                ShowMessages(
                    "please specify a correct hex value or an expression to put on the msr\n\n");
                CommandWrmsrHelp();
                return;
            }
            else
            {
                SetValue = TRUE;
                continue;
            }
        }
    }
 
    //
    // Check if msr is set or not
    //
    if (!SetMsr)
    {
        ShowMessages("please specify a correct hex value to write\n\n");
        CommandWrmsrHelp();
        return;
    }
 
    if (!SetValue)
    {
        ShowMessages("please specify a correct hex value to put on msr\n\n");
        CommandWrmsrHelp();
        return;
    }
 
    if (IsNextCoreId)
    {
        ShowMessages("please specify a correct hex value for core\n\n");
        CommandWrmsrHelp();
        return;
    }
 
    AssertShowMessageReturnStmt(g_IsKdModuleLoaded, g_DeviceHandle, ASSERT_MESSAGE_KD_NOT_LOADED, ASSERT_MESSAGE_DRIVER_NOT_LOADED, AssertReturn);
 
    MsrWriteRequest.ActionType = DEBUGGER_MSR_WRITE;
    MsrWriteRequest.Msr        = Msr;
    MsrWriteRequest.CoreNumber = CoreNumer;
    MsrWriteRequest.Value      = Value;
 
    Status = DeviceIoControl(
        g_DeviceHandle,                        // Handle to device
        IOCTL_DEBUGGER_READ_OR_WRITE_MSR,      // IO Control Code (IOCTL)
        &MsrWriteRequest,                      // Input Buffer to driver.
        SIZEOF_DEBUGGER_READ_AND_WRITE_ON_MSR, // Input buffer length
        &MsrWriteRequest,                      // Output Buffer from driver.
        SIZEOF_DEBUGGER_READ_AND_WRITE_ON_MSR, // Length of output buffer in bytes.
        &ReturnedLength,                       // Bytes placed in buffer.
        NULL                                   // synchronous call
    );
 
    if (!Status)
    {
        ShowMessages("ioctl failed with code (%x), either msr index or core id is invalid\n",
                     GetLastError());
        return;
    }
 
    ShowMessages("\n");
}

CommandWrmsrHelp()

VOID CommandWrmsrHelp

(

)

help of the wrmsr command

Returns

VOID

{
    ShowMessages("wrmsr : writes on a model-specific register (MSR).\n\n");
 
    ShowMessages("syntax : \twrmsr [Msr (hex)] [Value (hex)] [core CoreNumber (hex)]\n");
 
    ShowMessages("\n");
    ShowMessages("\t\te.g : wrmsr c0000082 fffff8077356f010\n");
    ShowMessages("\t\te.g : wrmsr c0000082 @rcx\n");
    ShowMessages("\t\te.g : wrmsr c0000082 @rcx+@rdx+12\n");
    ShowMessages("\t\te.g : wrmsr c0000082 fffff8077356f010 core 2\n");
}

Variable Documentation

g_IsKdModuleLoaded

BOOLEAN g_IsKdModuleLoaded

extern

shows whether the kernel debugger (KD) module is loaded or not