ArmPlatformPkg/NorFlashDxe: use strictly aligned CopyMem()
The UEFI spec stipulates that unaligned accesses should be enabled
on CPUs that support them, which means all of them, given that we
no longer support pre-v7 ARM cores, and the AARCH64 bindings mandate
support for unaligned accesses unconditionally.
This means that one should not assume that CopyMem () is safe to call
on regions that may be mapped using device attributes, which is the
case for the NOR flash. Since we have no control over the mappings when
running under the OS, and given that write accesses require device
mappings, we should not call CopyMem () in the read path either, but
use our own implementation that is guaranteed to take alignment into
account.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
diff --git a/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe.c b/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe.c
index 3abbe5c..ca61ac5 100644
--- a/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe.c
+++ b/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe.c
@@ -744,6 +744,65 @@
return Status;
}
+#define BOTH_ALIGNED(a, b, align) ((((UINTN)(a) | (UINTN)(b)) & ((align) - 1)) == 0)
+
+/**
+ Copy Length bytes from Source to Destination, using aligned accesses only.
+ Note that this implementation uses memcpy() semantics rather then memmove()
+ semantics, i.e., SourceBuffer and DestinationBuffer should not overlap.
+
+ @param DestinationBuffer The target of the copy request.
+ @param SourceBuffer The place to copy from.
+ @param Length The number of bytes to copy.
+
+ @return Destination
+
+**/
+STATIC
+VOID *
+AlignedCopyMem (
+ OUT VOID *DestinationBuffer,
+ IN CONST VOID *SourceBuffer,
+ IN UINTN Length
+ )
+{
+ UINT8 *Destination8;
+ CONST UINT8 *Source8;
+ UINT32 *Destination32;
+ CONST UINT32 *Source32;
+ UINT64 *Destination64;
+ CONST UINT64 *Source64;
+
+ if (BOTH_ALIGNED(DestinationBuffer, SourceBuffer, 8) && Length >= 8) {
+ Destination64 = DestinationBuffer;
+ Source64 = SourceBuffer;
+ while (Length >= 8) {
+ *Destination64++ = *Source64++;
+ Length -= 8;
+ }
+
+ Destination8 = (UINT8 *)Destination64;
+ Source8 = (CONST UINT8 *)Source64;
+ } else if (BOTH_ALIGNED(DestinationBuffer, SourceBuffer, 4) && Length >= 4) {
+ Destination32 = DestinationBuffer;
+ Source32 = SourceBuffer;
+ while (Length >= 4) {
+ *Destination32++ = *Source32++;
+ Length -= 4;
+ }
+
+ Destination8 = (UINT8 *)Destination32;
+ Source8 = (CONST UINT8 *)Source32;
+ } else {
+ Destination8 = DestinationBuffer;
+ Source8 = SourceBuffer;
+ }
+ while (Length-- != 0) {
+ *Destination8++ = *Source8++;
+ }
+ return DestinationBuffer;
+}
+
EFI_STATUS
NorFlashReadBlocks (
IN NOR_FLASH_INSTANCE *Instance,
@@ -791,7 +850,7 @@
SEND_NOR_COMMAND (Instance->DeviceBaseAddress, 0, P30_CMD_READ_ARRAY);
// Readout the data
- CopyMem(Buffer, (UINTN *)StartAddress, BufferSizeInBytes);
+ AlignedCopyMem (Buffer, (VOID *)StartAddress, BufferSizeInBytes);
return EFI_SUCCESS;
}
@@ -832,7 +891,7 @@
SEND_NOR_COMMAND (Instance->DeviceBaseAddress, 0, P30_CMD_READ_ARRAY);
// Readout the data
- CopyMem (Buffer, (UINTN *)(StartAddress + Offset), BufferSizeInBytes);
+ AlignedCopyMem (Buffer, (VOID *)StartAddress + Offset, BufferSizeInBytes);
return EFI_SUCCESS;
}
