205 lines
6.2 KiB
C++
205 lines
6.2 KiB
C++
/*
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Copyright (c) 1998-2000 Microsoft Corporation. All rights reserved.
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*/
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//
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// KernHelp.cpp
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//
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// Wrappers for kernel functions to make synth core cross compilable
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//
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#define STR_MODULENAME "DDKSynth.sys:KernHelp: "
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extern "C" {
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#include <wdm.h>
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};
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#include "ksdebug.h"
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#include "KernHelp.h"
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#pragma code_seg()
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/*****************************************************************************
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* InitializeCriticalSection()
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*****************************************************************************
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* In kernel mode, we use a KMUTEX to implement our critical section.
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* Initialize the KMUTEX.
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*/
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VOID InitializeCriticalSection(LPCRITICAL_SECTION CritSect)
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{
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KeInitializeMutex((PKMUTEX)CritSect, 1);
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}
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/*****************************************************************************
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* EnterCriticalSection()
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*****************************************************************************
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* In kernel mode, we use a KMUTEX to implement our critical section.
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* Grab (wait for) the KMUTEX.
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*/
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VOID EnterCriticalSection(LPCRITICAL_SECTION CritSect)
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{
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KeWaitForSingleObject((PKMUTEX)CritSect,
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Executive,
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KernelMode,
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FALSE,
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0);
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}
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/*****************************************************************************
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* LeaveCriticalSection()
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*****************************************************************************
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* In kernel mode, we use a KMUTEX to implement our critical section.
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* Release the KMUTEX.
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*/
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VOID LeaveCriticalSection(LPCRITICAL_SECTION CritSect)
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{
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KeReleaseMutex((PKMUTEX)CritSect, FALSE);
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}
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/*****************************************************************************
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* DeleteCriticalSection()
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*****************************************************************************
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* In kernel mode, we use a KMUTEX to implement our critical section.
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* No need to delete anything.
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*/
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VOID DeleteCriticalSection(LPCRITICAL_SECTION CritSect)
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{
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// NOP in kernel
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//
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}
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// GetRegValueDword
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//
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// Must be called at passive level
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//
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/*****************************************************************************
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* GetRegValueDword()
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*****************************************************************************
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* Convenience function to encapsulate registry reads.
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*/
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int GetRegValueDword(LPTSTR RegPath,LPTSTR ValueName,PULONG Value)
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{
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int ReturnValue = 0;
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NTSTATUS Status;
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OBJECT_ATTRIBUTES ObjectAttributes;
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HANDLE KeyHandle;
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KEY_VALUE_PARTIAL_INFORMATION *Information;
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ULONG InformationSize;
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UNICODE_STRING UnicodeRegPath;
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UNICODE_STRING UnicodeValueName;
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RtlInitUnicodeString(&UnicodeRegPath, RegPath);
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RtlInitUnicodeString(&UnicodeValueName, ValueName);
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InitializeObjectAttributes(&ObjectAttributes,
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&UnicodeRegPath,
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OBJ_KERNEL_HANDLE, // Flags
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NULL, // Root directory
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NULL); // Security descriptor
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Status = ZwOpenKey(&KeyHandle,
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KEY_QUERY_VALUE,
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&ObjectAttributes);
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if (Status != STATUS_SUCCESS)
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{
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return 0;
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}
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InformationSize = sizeof(KEY_VALUE_PARTIAL_INFORMATION) + sizeof(ULONG);
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Information = (KEY_VALUE_PARTIAL_INFORMATION*)ExAllocatePoolWithTag(PagedPool, InformationSize,'ISmD'); // DmSI
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if (Information == NULL)
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{
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ZwClose(KeyHandle);
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return 0;
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}
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Status = ZwQueryValueKey(KeyHandle,
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&UnicodeValueName,
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KeyValuePartialInformation,
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Information,
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sizeof(Information),
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&InformationSize);
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if (Status == STATUS_SUCCESS)
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{
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if (Information->Type == REG_DWORD && Information->DataLength == sizeof(ULONG))
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{
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RtlCopyMemory(Value, Information->Data, sizeof(ULONG));
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ReturnValue = 1;
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}
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}
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ExFreePool(Information);
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ZwClose(KeyHandle);
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return ReturnValue;
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}
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/*****************************************************************************
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* GetTheCurrentTime()
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*****************************************************************************
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* Get the current time, in milliseconds (KeQuerySystemTime returns units of
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* 100ns each).
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*/
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ULONG GetTheCurrentTime()
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{
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LARGE_INTEGER Time;
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KeQuerySystemTime(&Time);
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return (ULONG)(Time.QuadPart / (10 * 1000));
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}
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/*****************************************************************************
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* KernHelpGetSysAddrForMdl()
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*****************************************************************************
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* Safely map the MDL to system address space. This mapping
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* may fail "when the system runs out of system PTEs", and
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* without the flag set below, this condition causes a bugcheck
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* rather than a NULL return.
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*/
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PVOID KernHelpGetSysAddrForMdl(PMDL pMdl)
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{
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PVOID MappedAddress;
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#if UNDER_NT
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MappedAddress = MmGetSystemAddressForMdlSafe(pMdl,NormalPagePriority);
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#else // !UNDER_NT
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CSHORT LocalCopyOfMdlFlagBit;
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//
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// Note the manipulation of the MDL flags is only done if needed.
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// The driver is responsible for ensuring that it is not simultaneously
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// modifying this field anywhere else and synchronizing if needed.
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//
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LocalCopyOfMdlFlagBit = (pMdl->MdlFlags & MDL_MAPPING_CAN_FAIL);
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if (LocalCopyOfMdlFlagBit == 0)
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{
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pMdl->MdlFlags |= MDL_MAPPING_CAN_FAIL;
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}
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MappedAddress = MmGetSystemAddressForMdl(pMdl);
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//
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// Carefully restore only the single "can-fail" bit state. This is
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// because the call above will change the state of other flag bits and
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// we don't want this restore to wipe out those changes. Wiping out the
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// other changes will cause not-so-obvious effects like eventually
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// exhausting the system PTE pool and other resources, which will crash
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// the entire system.
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//
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if (LocalCopyOfMdlFlagBit == 0)
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{
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pMdl->MdlFlags &= ~MDL_MAPPING_CAN_FAIL;
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}
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#endif // !UNDER_NT
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return MappedAddress;
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}
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