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ArmPkg/ArmDmaLib: reject consistent DMA mappings of cached memory 

DmaMap () operations of type MapOperationBusMasterCommonBuffer should
return a mapping that is coherent between the CPU and the device. For
this reason, the API only allows DmaMap () to be called with this operation
type if the memory to be mapped was allocated by DmaAllocateBuffer (),
which in this implementation guarantees the coherency by using uncached
mappings on the CPU side.

This means that, if we encounter a cached mapping in DmaMap () with this
operation type, the code is either broken, or someone is violating the
API, but simply proceeding with a double buffer makes no sense at all,
and can only cause problems.

So instead, actively reject this operation type for cached memory mappings.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
This commit is contained in:
Ard Biesheuvel 2016-04-19 16:26:00 +02:00
parent 885d57ef09
commit a24f7d6680
1 changed files with 23 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
View File

@ -103,6 +103,18 @@ DmaMap (
// If the mapped buffer is not an uncached buffer
if ((GcdDescriptor.Attributes & (EFI_MEMORY_WB | EFI_MEMORY_WT)) != 0) {
//
// Operations of type MapOperationBusMasterCommonBuffer are only allowed
// on uncached buffers.
//
if (Operation == MapOperationBusMasterCommonBuffer) {
DEBUG ((EFI_D_ERROR,
"%a: Operation type 'MapOperationBusMasterCommonBuffer' is only supported\n"
"on memory regions that were allocated using DmaAllocateBuffer ()\n",
__FUNCTION__));
return EFI_UNSUPPORTED;
}
//
// If the buffer does not fill entire cache lines we must double buffer into
// uncached memory. Device (PCI) address becomes uncached page.
@ -113,7 +125,7 @@ DmaMap (
return Status;
}
if ((Operation == MapOperationBusMasterRead) || (Operation == MapOperationBusMasterCommonBuffer)) {
if (Operation == MapOperationBusMasterRead) {
CopyMem (Buffer, HostAddress, *NumberOfBytes);
}
@ -151,6 +163,8 @@ DmaMap (
@retval EFI_SUCCESS The range was unmapped.
@retval EFI_DEVICE_ERROR The data was not committed to the target system memory.
@retval EFI_INVALID_PARAMETER An inconsistency was detected between the mapping type
and the DoubleBuffer field
**/
EFI_STATUS
@ -160,6 +174,7 @@ DmaUnmap (
)
{
MAP_INFO_INSTANCE *Map;
EFI_STATUS Status;
if (Mapping == NULL) {
ASSERT (FALSE);
@ -168,8 +183,13 @@ DmaUnmap (
Map = (MAP_INFO_INSTANCE *)Mapping;
Status = EFI_SUCCESS;
if (Map->DoubleBuffer) {
if ((Map->Operation == MapOperationBusMasterWrite) || (Map->Operation == MapOperationBusMasterCommonBuffer)) {
ASSERT (Map->Operation != MapOperationBusMasterCommonBuffer);
if (Map->Operation == MapOperationBusMasterCommonBuffer) {
Status = EFI_INVALID_PARAMETER;
} else if (Map->Operation == MapOperationBusMasterWrite) {
CopyMem ((VOID *)(UINTN)Map->HostAddress, (VOID *)(UINTN)Map->DeviceAddress, Map->NumberOfBytes);
}
@ -186,7 +206,7 @@ DmaUnmap (
FreePool (Map);
return EFI_SUCCESS;
return Status;
}
/**