mirror of https://github.com/acidanthera/audk.git
132 lines
4.1 KiB
C
132 lines
4.1 KiB
C
/** @file
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Utility functions for serializing (persistently storing) and deserializing
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OVMF's platform configuration.
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Copyright (C) 2014, Red Hat, Inc.
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This program and the accompanying materials are licensed and made available
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under the terms and conditions of the BSD License which accompanies this
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distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
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WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include <Library/BaseMemoryLib.h>
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#include <Library/DebugLib.h>
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#include <Library/MemoryAllocationLib.h>
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#include <Library/UefiLib.h>
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#include <Library/UefiRuntimeServicesTableLib.h>
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#include <Guid/OvmfPlatformConfig.h>
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#include "PlatformConfig.h"
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//
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// Name of the UEFI variable that we use for persistent storage.
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//
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STATIC CHAR16 mVariableName[] = L"PlatformConfig";
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/**
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Serialize and persistently save platform configuration.
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@param[in] PlatformConfig The platform configuration to serialize and save.
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@return Status codes returned by gRT->SetVariable().
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**/
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EFI_STATUS
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EFIAPI
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PlatformConfigSave (
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IN PLATFORM_CONFIG *PlatformConfig
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)
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{
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EFI_STATUS Status;
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//
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// We could implement any kind of translation here, as part of serialization.
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// For example, we could expose the platform configuration in separate
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// variables with human-readable contents, allowing other tools to access
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// them more easily. For now, just save a binary dump.
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//
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Status = gRT->SetVariable (mVariableName, &gOvmfPlatformConfigGuid,
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EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS |
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EFI_VARIABLE_RUNTIME_ACCESS,
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sizeof *PlatformConfig, PlatformConfig);
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return Status;
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}
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/**
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Load and deserialize platform configuration.
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When the function fails, output parameters are indeterminate.
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@param[out] PlatformConfig The platform configuration to receive the
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loaded data.
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@param[out] OptionalElements This bitmap describes the presence of optional
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configuration elements that have been loaded.
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PLATFORM_CONFIG_F_DOWNGRADE means that some
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unknown elements, present in the wire format,
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have been ignored.
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@retval EFI_SUCCESS Loading & deserialization successful.
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@return Error codes returned by GetVariable2().
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**/
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EFI_STATUS
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EFIAPI
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PlatformConfigLoad (
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OUT PLATFORM_CONFIG *PlatformConfig,
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OUT UINT64 *OptionalElements
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)
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{
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VOID *Data;
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UINTN DataSize;
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EFI_STATUS Status;
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//
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// Any translation done in PlatformConfigSave() would have to be mirrored
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// here. For now, just load the binary dump.
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//
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// Versioning of the binary wire format is implemented based on size
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// (only incremental changes, ie. new fields), and on GUID.
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// (Incompatible changes require a GUID change.)
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//
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Status = GetVariable2 (mVariableName, &gOvmfPlatformConfigGuid, &Data,
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&DataSize);
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if (EFI_ERROR (Status)) {
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return Status;
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}
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*OptionalElements = 0;
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if (DataSize > sizeof *PlatformConfig) {
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//
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// Handle firmware downgrade -- keep only leading part.
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//
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CopyMem (PlatformConfig, Data, sizeof *PlatformConfig);
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*OptionalElements |= PLATFORM_CONFIG_F_DOWNGRADE;
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} else {
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CopyMem (PlatformConfig, Data, DataSize);
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//
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// Handle firmware upgrade -- zero out missing fields.
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//
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ZeroMem ((UINT8 *)PlatformConfig + DataSize,
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sizeof *PlatformConfig - DataSize);
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}
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//
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// Based on DataSize, report the optional features that we recognize.
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//
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if (DataSize >= (OFFSET_OF (PLATFORM_CONFIG, VerticalResolution) +
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sizeof PlatformConfig->VerticalResolution)) {
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*OptionalElements |= PLATFORM_CONFIG_F_GRAPHICS_RESOLUTION;
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}
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FreePool (Data);
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return EFI_SUCCESS;
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}
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