tyler.durden
/
audk
mirror of https://github.com/acidanthera/audk.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

ArmPkg/ArmDmaLib: do not remap arbitrary memory regions as uncached 

In the DmaMap () operation, if the region to be mapped happens to be
aligned to the Cache Writeback Granule (CWG) (whose value is typically
64 or 128 bytes and 2 KB maximum), we remap the memory as uncached.

Since remapping memory occurs at page granularity, while the buffer and the
CWG may be much smaller, there is no telling what other memory we affect
by doing this, especially since the operation is not reverted in DmaUnmap().

So remove the remapping call.

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 16:37:04 +02:00
parent a24f7d6680
commit 32e5fb76e5
1 changed files with 0 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
ArmPkg/Library/ArmDmaLib/ArmDmaLib.c
View File

@ -138,12 +138,6 @@ DmaMap (
// Flush the Data Cache (should not have any effect if the memory region is uncached)
gCpu->FlushDataCache (gCpu, *DeviceAddress, *NumberOfBytes, EfiCpuFlushTypeWriteBackInvalidate);
if ((Operation == MapOperationBusMasterRead) || (Operation == MapOperationBusMasterCommonBuffer)) {
// In case the buffer is used for instance to send command to a PCI controller, we must ensure the memory is uncached
Status = gDS->SetMemorySpaceAttributes (*DeviceAddress & ~(BASE_4KB - 1), ALIGN_VALUE (*NumberOfBytes, BASE_4KB), EFI_MEMORY_WC);
ASSERT_EFI_ERROR (Status);
}
}
Map->HostAddress = (UINTN)HostAddress;