Re: Getting same physical address for 2 different user addresses.

Thanks Mark, Daniel and Tim for your response.

We are allocating the buffers readbuf and writebuf in the application using
malloc.

readbuf = malloc(nof pages * 4K);
Then we are sending this buffer as inputbuffer to Driver using IOCTL defined
as METHOD_IN_DIRECT.

writebuf = malloc(nof pages * 4K);
Then we are sending this buffer as inputbuffer to Driver using IOCTL defined
as METHOD_IN_DIRECT.

Here is the driver code handles the Physical Address conversion,


NTSTATUS LockUserModeMemory(
PDEVICE_EXTENSION pDevExt,
WDF_REQUEST_PARAMETERS UserModeMemLockParams,
IN WDFREQUEST UserModeMemLockRequest,
ULONG *pDataLockedMemSize){

NTSTATUS ntStatus = STATUS_SUCCESS;
PVOID pUserModeMemLockOutputBuffer = NULL;
PVOID pUserModeMemLockInputBuffer = NULL;
size_t UserModeMemLockOutputBufSize;
size_t UserModeMemLockInputBufSize;

PLOCK_USER_MODE_MEMORY_INPARAMS pLockUserModeMemInParams= NULL;
PLOCK_USER_MODE_MEMORY_OUTPARAMS pLockUserModeMemOutParams= NULL;


PVOID pIoMapedBaseVa = NULL;
PVOID pTempLockedMem = NULL;
PVOID pTempLockedPage = NULL;
PHYSICAL_ADDRESS UserModeMemLockPhyAddr;
PHYSICAL_ADDRESS lowAddress;
PHYSICAL_ADDRESS highAddress;
ULONG ulIndex=0;
PMDL pDmaMdl;
ULONG ulSize=0;
PVOID inBuf, outBuf;
PVOID reqContext = NULL;
size_t inBufLen,outBufLen;

WDF_OBJECT_ATTRIBUTES attributes;

UCHAR *pTempUserModeBufStart;
PVOID pUserModeBuff = NULL;
ULONG ulNoOfPages=0;

KIRQL kOldIrql;
KIRQL kCurrentIrql;

DbgPrint("%s--->\n",__FUNCTION__);

if(UserModeMemLockParams.Parameters.DeviceIoControl.InputBufferLength<=0){
DbgPrint("Buff size is small\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INVALID_PARAMETER;
goto EXIT;
}

pDevExt->ulPageNeeded=0;
ntStatus = WdfRequestRetrieveInputBuffer(
UserModeMemLockRequest,
UserModeMemLockParams.Parameters.DeviceIoControl.InputBufferLength,
&pUserModeBuff,
&UserModeMemLockInputBufSize);

if( !NT_SUCCESS(ntStatus) ){
DbgPrint("WdfRequestRetrieveInputBuffer is failed\n");
*pDataLockedMemSize = 0;
goto EXIT;
}

if(pUserModeBuff == NULL){
DbgPrint("WdfRequestRetrieveInputBuffer is failed\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
goto EXIT;
}

ulNoOfPages=UserModeMemLockParams.Parameters.DeviceIoControl.InputBufferLength/PAGE_SIZE;

if((UserModeMemLockParams.Parameters.DeviceIoControl.InputBufferLength%PAGE_SIZE)!= 0){
ulNoOfPages++;
}

ntStatus = WdfRequestRetrieveOutputBuffer(
UserModeMemLockRequest,
(ulNoOfPages*sizeof(LOCK_USER_MODE_MEMORY_OUTPARAMS)),
&pUserModeMemLockOutputBuffer,
&UserModeMemLockOutputBufSize);

if( !NT_SUCCESS(ntStatus) ){
DbgPrint("WdfRequestRetrieveOutputBuffer is failed\n");
*pDataLockedMemSize = 0;
goto EXIT;
}

if(pUserModeMemLockOutputBuffer == NULL){
DbgPrint("WdfRequestRetrieveOutputBuffer is failed\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
goto EXIT;
}

if(UserModeMemLockParams.Parameters.DeviceIoControl.OutputBufferLength<(ulNoOfPages*sizeof(LOCK_USER_MODE_MEMORY_OUTPARAMS))){
DbgPrint("Buff size is small\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INVALID_PARAMETER;
goto EXIT;
}

pLockUserModeMemOutParams= (PLOCK_USER_MODE_MEMORY_OUTPARAMS)pUserModeMemLockOutputBuffer;

kCurrentIrql = KeGetCurrentIrql();
KeLowerIrql(APC_LEVEL);

pTempUserModeBufStart = (UCHAR *)pUserModeBuff;

for(ulIndex=0,ulSize=UserModeMemLockParams.Parameters.DeviceIoControl.InputBufferLength;ulIndex<ulNoOfPages;ulIndex++){
DbgPrint("ulIndex:%u\n",ulIndex);
if(ulSize>=4096){
pDmaMdl = IoAllocateMdl((PVOID)
pTempUserModeBufStart,
4096,
FALSE,
FALSE,
NULL //Irp OPTIONAL);

if(pDmaMdl == NULL){
DbgPrint("IoAllocateMdl failed\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
goto RAISE_IRQL;
}

MmProbeAndLockPages(pDmaMdl,KernelMode ,IoModifyAccess);
//UserMode
pTempLockedPage = MmMapLockedPagesSpecifyCache(pDmaMdl,KernelMode,MmCached,NULL,FALSE,NormalPagePriority);

if(pTempLockedPage == NULL){
MmUnlockPages(pDmaMdl);
IoFreeMdl(pDmaMdl);
DbgPrint("IoAllocateMdl failed\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
goto RAISE_IRQL;
}

UserModeMemLockPhyAddr=MmGetPhysicalAddress(pTempLockedPage);

//for each page fill the following structure

pLockUserModeMemOutParams[ulIndex].ulNoOfBytes = 4096;
pLockUserModeMemOutParams[ulIndex].pCurrentPageMdl=(ULONG *)pDmaMdl;
pLockUserModeMemOutParams[ulIndex].pMappedLocked=(PVOID)pTempLockedPage;
pLockUserModeMemOutParams[ulIndex].ulUserModePhysicalAdd = UserModeMemLockPhyAddr.LowPart;

pTempUserModeBufStart+=4096;
ulSize-=4096;
}
else if(ulSize>0 && ulSize<4096) {
pDmaMdl = IoAllocateMdl(
(PVOID)
pTempUserModeBufStart,
ulSize,
FALSE,//SecondaryBuffer,
FALSE,//ChargeQuota,
NULL //Irp OPTIONAL );

if(pDmaMdl == NULL) {
DbgPrint("IoAllocateMdl failed\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
goto RAISE_IRQL;
}

MmProbeAndLockPages(pDmaMdl,KernelMode ,IoModifyAccess);

pTempLockedPage = MmMapLockedPagesSpecifyCache(pDmaMdl,UserMode,MmCached,NULL,FALSE,NormalPagePriority);

if(pTempLockedPage == NULL){
MmUnlockPages(pDmaMdl);
IoFreeMdl(pDmaMdl);
DbgPrint("IoAllocateMdl failed\n");
*pDataLockedMemSize = 0;
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
goto RAISE_IRQL;
}

UserModeMemLockPhyAddr=MmGetPhysicalAddress(pTempLockedPage);

pLockUserModeMemOutParams[ulIndex].ulNoOfBytes = ulSize;
pLockUserModeMemOutParams[ulIndex].pMappedLocked = (PVOID)pTempLockedPage;
pLockUserModeMemOutParams[ulIndex].pCurrentPageMdl = (ULONG *)pDmaMdl;
pLockUserModeMemOutParams[ulIndex].ulUserModePhysicalAdd = UserModeMemLockPhyAddr.LowPart;

pTempUserModeBufStart+=ulSize;
ulSize-=ulSize;

}
}

pDevExt->ulPageNeeded =ulNoOfPages;
*pDataLockedMemSize
=UserModeMemLockParams.Parameters.DeviceIoControl.OutputBufferLength;

RAISE_IRQL:
KeRaiseIrql(kCurrentIrql,&kOldIrql);
EXIT:
DbgPrint("<---%s\n",__FUNCTION__);
return ntStatus;
}

Our issue is, UserModeMemLockPhyAddr.LowPart is the same for both readbuf
and writebuf.

Thanks,
Saravana
.

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