system76-edk2/SecurityPkg/VariableAuthenticated/RuntimeDxe/Reclaim.c

/** @file
  Handles non-volatile variable store garbage collection, using FTW
  (Fault Tolerant Write) protocol.

Copyright (c) 2009 - 2014, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials 
are licensed and made available under the terms and conditions of the BSD License 
which accompanies this distribution.  The full text of the license may be found at 
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "Variable.h"

/**
  Gets LBA of block and offset by given address.

  This function gets the Logical Block Address (LBA) of a firmware
  volume block containing the given address, and the offset of the
  address on the block.

  @param  Address        Address which should be contained
                         by returned FVB handle.
  @param  Lba            Pointer to LBA for output.
  @param  Offset         Pointer to offset for output.

  @retval EFI_SUCCESS    LBA and offset successfully returned.
  @retval EFI_NOT_FOUND  Fail to find FVB handle by address.
  @retval EFI_ABORTED    Fail to find valid LBA and offset.

**/
EFI_STATUS
GetLbaAndOffsetByAddress (
  IN  EFI_PHYSICAL_ADDRESS   Address,
  OUT EFI_LBA                *Lba,
  OUT UINTN                  *Offset
  )
{
  EFI_STATUS                          Status;
  EFI_PHYSICAL_ADDRESS                FvbBaseAddress;
  EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL  *Fvb;
  EFI_FIRMWARE_VOLUME_HEADER          *FwVolHeader;
  EFI_FV_BLOCK_MAP_ENTRY              *FvbMapEntry;
  UINT32                              LbaIndex;

  *Lba    = (EFI_LBA) (-1);
  *Offset = 0;
  Fvb = NULL;

  //
  // Get the proper FVB protocol.
  //
  Status = GetFvbInfoByAddress (Address, NULL, &Fvb);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Get the Base Address of FV.
  //
  Status = Fvb->GetPhysicalAddress (Fvb, &FvbBaseAddress);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  FwVolHeader = (EFI_FIRMWARE_VOLUME_HEADER *) ((UINTN) FvbBaseAddress);

  //
  // Get the (LBA, Offset) of Address.
  //
  if ((FwVolHeader->FvLength) > (FwVolHeader->HeaderLength)) {
    //
    // BUGBUG: Assume one FV has one type of BlockLength.
    //
    FvbMapEntry = &FwVolHeader->BlockMap[0];
    for (LbaIndex = 1; LbaIndex <= FvbMapEntry->NumBlocks; LbaIndex += 1) {
      if (Address < (FvbBaseAddress + FvbMapEntry->Length * LbaIndex)) {
        //
        // Found the (Lba, Offset).
        //
        *Lba    = LbaIndex - 1;
        *Offset = (UINTN) (Address - (FvbBaseAddress + FvbMapEntry->Length * (LbaIndex - 1)));
        return EFI_SUCCESS;
     }
    }
  }

  return EFI_ABORTED;
}

/**
  Writes a buffer to variable storage space, in the working block.

  This function writes a buffer to variable storage space into a firmware
  volume block device. The destination is specified by parameter
  VariableBase. Fault Tolerant Write protocol is used for writing.

  @param  VariableBase   Base address of variable to write
  @param  VariableBuffer Point to the variable data buffer.

  @retval EFI_SUCCESS    The function completed successfully.
  @retval EFI_NOT_FOUND  Fail to locate Fault Tolerant Write protocol.
  @retval EFI_ABORTED    The function could not complete successfully.

**/
EFI_STATUS
FtwVariableSpace (
  IN EFI_PHYSICAL_ADDRESS   VariableBase,
  IN VARIABLE_STORE_HEADER  *VariableBuffer
  )
{
  EFI_STATUS                         Status;
  EFI_HANDLE                         FvbHandle;
  EFI_LBA                            VarLba;
  UINTN                              VarOffset;
  UINTN                              FtwBufferSize;
  EFI_FAULT_TOLERANT_WRITE_PROTOCOL  *FtwProtocol;

  //
  // Locate fault tolerant write protocol.
  //
  Status = GetFtwProtocol((VOID **) &FtwProtocol);
  if (EFI_ERROR (Status)) {
    return EFI_NOT_FOUND;
  }
  //
  // Locate Fvb handle by address.
  //
  Status = GetFvbInfoByAddress (VariableBase, &FvbHandle, NULL);
  if (EFI_ERROR (Status)) {
    return Status;
  }
  //
  // Get LBA and Offset by address.
  //
  Status = GetLbaAndOffsetByAddress (VariableBase, &VarLba, &VarOffset);
  if (EFI_ERROR (Status)) {
    return EFI_ABORTED;
  }

  FtwBufferSize = ((VARIABLE_STORE_HEADER *) ((UINTN) VariableBase))->Size;
  ASSERT (FtwBufferSize == VariableBuffer->Size);

  //
  // FTW write record.
  //
  Status = FtwProtocol->Write (
                          FtwProtocol,
                          VarLba,         // LBA
                          VarOffset,      // Offset
                          FtwBufferSize,  // NumBytes
                          NULL,           // PrivateData NULL
                          FvbHandle,      // Fvb Handle
                          (VOID *) VariableBuffer // write buffer
                          );

  return Status;
}