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7835e5802a
Replace traditional `#ifndef`/`#define`/`#endif` include guards with
`#pragma` once.
`#pragma once` is a widely supported preprocessor directive that
prevents header files from being included multiple times. It is
supported by all toolchains used to build edk2: GCC, Clang/LLVM, and
MSVC.
Compared to macro-based include guards, `#pragma once`:
- Eliminates the risk of macro name collisions or copy/paste errors
where two headers inadvertently use the same guard macro.
- Eliminate inconsistency in the way include guard macros are named
(e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.).
- Reduces boilerplate (three lines replaced by one).
- Avoids polluting the macro namespace with guard symbols.
- Can improve build times as the preprocessor can skip re-opening the
file entirely, rather than re-reading it to find the matching
`#endif` ("multiple-include optimization").
- Note that some compilers may already optimize traditional include
guards, by recognzining the idiomatic pattern.
This change is made acknowledging that overall portability of the
code will technically be reduced, as `#pragma once` is not part of the
C/C++ standards.
However, this is considered acceptable given:
1. edk2 already defines a subset of supported compilers in
BaseTools/Conf/tools_def.template, all of which have supported
`#pragma once` for over two decades.
2. There have been concerns raised to the project about inconsistent
include guard naming and potential macro collisions.
Approximate compiler support dates:
- MSVC: Supported since Visual C++ 4.2 (1996)
- GCC: Supported since 3.4 (2004)
(http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html)
- Clang (LLVM based): Since initial release in 2007
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
67 lines
2.2 KiB
C
67 lines
2.2 KiB
C
/** @file
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GUID used for MemoryOverwriteRequestControl UEFI variable defined in
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TCG Platform Reset Attack Mitigation Specification 1.00.
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See http://trustedcomputinggroup.org for the latest specification
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The purpose of the MemoryOverwriteRequestControl UEFI variable is to give users (e.g., OS, loader) the ability to
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indicate to the platform that secrets are present in memory and that the platform firmware must clear memory upon
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a restart. The OS loader should not create the variable. Rather, the firmware is required to create it.
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Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#pragma once
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#define MEMORY_ONLY_RESET_CONTROL_GUID \
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{ \
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0xe20939be, 0x32d4, 0x41be, {0xa1, 0x50, 0x89, 0x7f, 0x85, 0xd4, 0x98, 0x29} \
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}
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///
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/// Variable name is "MemoryOverwriteRequestControl" and it is a 1 byte unsigned value.
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/// The attributes should be:
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/// EFI_VARIABLE_NON_VOLATILE |
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/// EFI_VARIABLE_BOOTSERVICE_ACCESS |
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/// EFI_VARIABLE_RUNTIME_ACCESS
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///
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#define MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME L"MemoryOverwriteRequestControl"
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///
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/// 0 = Firmware MUST clear the MOR bit
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/// 1 = Firmware MUST set the MOR bit
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///
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#define MOR_CLEAR_MEMORY_BIT_MASK 0x01
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///
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/// 0 = Firmware MAY autodetect a clean shutdown of the Static RTM OS.
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/// 1 = Firmware MUST NOT autodetect a clean shutdown of the Static RTM OS.
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///
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#define MOR_DISABLEAUTODETECT_BIT_MASK 0x10
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///
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/// MOR field bit offset
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///
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#define MOR_CLEAR_MEMORY_BIT_OFFSET 0
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#define MOR_DISABLEAUTODETECT_BIT_OFFSET 4
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/**
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Return the ClearMemory bit value 0 or 1.
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@param mor 1 byte value that contains ClearMemory and DisableAutoDetect bit.
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@return ClearMemory bit value
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**/
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#define MOR_CLEAR_MEMORY_VALUE(mor) (((UINT8)(mor) & MOR_CLEAR_MEMORY_BIT_MASK) >> MOR_CLEAR_MEMORY_BIT_OFFSET)
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/**
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Return the DisableAutoDetect bit value 0 or 1.
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@param mor 1 byte value that contains ClearMemory and DisableAutoDetect bit.
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@return DisableAutoDetect bit value
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**/
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#define MOR_DISABLE_AUTO_DETECT_VALUE(mor) (((UINT8)(mor) & MOR_DISABLEAUTODETECT_BIT_MASK) >> MOR_DISABLEAUTODETECT_BIT_OFFSET)
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extern EFI_GUID gEfiMemoryOverwriteControlDataGuid;
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