system76-edk2/MdeModulePkg/Bus/Pci/NvmExpressPei/DevicePath.c

/** @file
  The device path help function.

  Copyright (c) 2019, 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 "NvmExpressPei.h"

//
// Template for an Nvm Express Device Path node
//
NVME_NAMESPACE_DEVICE_PATH  mNvmeDevicePathNodeTemplate = {
  {        // Header
    MESSAGING_DEVICE_PATH,
    MSG_NVME_NAMESPACE_DP,
    {
      (UINT8) (sizeof (NVME_NAMESPACE_DEVICE_PATH)),
      (UINT8) ((sizeof (NVME_NAMESPACE_DEVICE_PATH)) >> 8)
    }
  },
  0x0,     // NamespaceId
  0x0      // NamespaceUuid
};

//
// Template for an End of entire Device Path node
//
EFI_DEVICE_PATH_PROTOCOL  mNvmeEndDevicePathNodeTemplate = {
  END_DEVICE_PATH_TYPE,
  END_ENTIRE_DEVICE_PATH_SUBTYPE,
  {
    (UINT8) (sizeof (EFI_DEVICE_PATH_PROTOCOL)),
    (UINT8) ((sizeof (EFI_DEVICE_PATH_PROTOCOL)) >> 8)
  }
};

/**
  Returns the 16-bit Length field of a device path node.

  Returns the 16-bit Length field of the device path node specified by Node.
  Node is not required to be aligned on a 16-bit boundary, so it is recommended
  that a function such as ReadUnaligned16() be used to extract the contents of
  the Length field.

  If Node is NULL, then ASSERT().

  @param  Node      A pointer to a device path node data structure.

  @return The 16-bit Length field of the device path node specified by Node.

**/
UINTN
DevicePathNodeLength (
  IN CONST VOID  *Node
  )
{
  ASSERT (Node != NULL);
  return ReadUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0]);
}

/**
  Returns a pointer to the next node in a device path.

  If Node is NULL, then ASSERT().

  @param  Node    A pointer to a device path node data structure.

  @return a pointer to the device path node that follows the device path node
  specified by Node.

**/
EFI_DEVICE_PATH_PROTOCOL *
NextDevicePathNode (
  IN CONST VOID  *Node
  )
{
  ASSERT (Node != NULL);
  return (EFI_DEVICE_PATH_PROTOCOL *)((UINT8 *)(Node) + DevicePathNodeLength(Node));
}

/**
  Check the validity of the device path of a NVM Express host controller.

  @param[in] DevicePath          A pointer to the EFI_DEVICE_PATH_PROTOCOL
                                 structure.
  @param[in] DevicePathLength    The length of the device path.

  @retval EFI_SUCCESS              The device path is valid.
  @retval EFI_INVALID_PARAMETER    The device path is invalid.

**/
EFI_STATUS
NvmeIsHcDevicePathValid (
  IN EFI_DEVICE_PATH_PROTOCOL    *DevicePath,
  IN UINTN                       DevicePathLength
  )
{
  EFI_DEVICE_PATH_PROTOCOL    *Start;
  UINTN                       Size;

  if (DevicePath == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Validate the DevicePathLength is big enough to touch the first node.
  //
  if (DevicePathLength < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
    return EFI_INVALID_PARAMETER;
  }

  Start = DevicePath;
  while (!(DevicePath->Type == END_DEVICE_PATH_TYPE &&
           DevicePath->SubType == END_ENTIRE_DEVICE_PATH_SUBTYPE)) {
    DevicePath = NextDevicePathNode (DevicePath);

    //
    // Prevent overflow and invalid zero in the 'Length' field of a device path
    // node.
    //
    if ((UINTN) DevicePath <= (UINTN) Start) {
      return EFI_INVALID_PARAMETER;
    }

    //
    // Prevent touching memory beyond given DevicePathLength.
    //
    if ((UINTN) DevicePath - (UINTN) Start >
        DevicePathLength - sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
      return EFI_INVALID_PARAMETER;
    }
  }

  //
  // Check if the device path and its size match exactly with each other.
  //
  Size = ((UINTN) DevicePath - (UINTN) Start) + sizeof (EFI_DEVICE_PATH_PROTOCOL);
  if (Size != DevicePathLength) {
    return EFI_INVALID_PARAMETER;
  }

  return EFI_SUCCESS;
}

/**
  Build the device path for an Nvm Express device with given namespace identifier
  and namespace extended unique identifier.

  @param[in]  Private              A pointer to the PEI_NVME_CONTROLLER_PRIVATE_DATA
                                   data structure.
  @param[in]  NamespaceId          The given namespace identifier.
  @param[in]  NamespaceUuid        The given namespace extended unique identifier.
  @param[out] DevicePathLength     The length of the device path in bytes specified
                                   by DevicePath.
  @param[out] DevicePath           The device path of Nvm Express device.

  @retval EFI_SUCCESS              The operation succeeds.
  @retval EFI_INVALID_PARAMETER    The parameters are invalid.
  @retval EFI_OUT_OF_RESOURCES     The operation fails due to lack of resources.

**/
EFI_STATUS
NvmeBuildDevicePath (
  IN  PEI_NVME_CONTROLLER_PRIVATE_DATA    *Private,
  IN  UINT32                              NamespaceId,
  IN  UINT64                              NamespaceUuid,
  OUT UINTN                               *DevicePathLength,
  OUT EFI_DEVICE_PATH_PROTOCOL            **DevicePath
  )
{
  EFI_DEVICE_PATH_PROTOCOL      *DevicePathWalker;
  NVME_NAMESPACE_DEVICE_PATH    *NvmeDeviceNode;

  if (DevicePathLength == NULL || DevicePath == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  *DevicePathLength = Private->DevicePathLength + sizeof (NVME_NAMESPACE_DEVICE_PATH);
  *DevicePath       = AllocatePool (*DevicePathLength);
  if (*DevicePath == NULL) {
    *DevicePathLength = 0;
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // Construct the host controller part device nodes
  //
  DevicePathWalker = *DevicePath;
  CopyMem (
    DevicePathWalker,
    Private->DevicePath,
    Private->DevicePathLength - sizeof (EFI_DEVICE_PATH_PROTOCOL)
    );

  //
  // Construct the Nvm Express device node
  //
  DevicePathWalker = (EFI_DEVICE_PATH_PROTOCOL *) ((UINT8 *)DevicePathWalker +
                     (Private->DevicePathLength - sizeof (EFI_DEVICE_PATH_PROTOCOL)));
  CopyMem (
    DevicePathWalker,
    &mNvmeDevicePathNodeTemplate,
    sizeof (mNvmeDevicePathNodeTemplate)
    );
  NvmeDeviceNode                = (NVME_NAMESPACE_DEVICE_PATH *)DevicePathWalker;
  NvmeDeviceNode->NamespaceId   = NamespaceId;
  NvmeDeviceNode->NamespaceUuid = NamespaceUuid;

  //
  // Construct the end device node
  //
  DevicePathWalker = (EFI_DEVICE_PATH_PROTOCOL *) ((UINT8 *)DevicePathWalker +
                     sizeof (NVME_NAMESPACE_DEVICE_PATH));
  CopyMem (
    DevicePathWalker,
    &mNvmeEndDevicePathNodeTemplate,
    sizeof (mNvmeEndDevicePathNodeTemplate)
    );

  return EFI_SUCCESS;
}