[PATCH V2 2/3] MdePkg/Base.h: Introduce various alignment-related macros

["Marvin Häuser" <mhaeuser@posteo.de>]

ALIGNOF: Determining the alignment requirement of data types is
crucial to ensure safe memory accesses when parsing untrusted data.

IS_POW2: Determining whether a value is a power of two is important
to verify whether untrusted values are valid alignment values.

IS_ALIGNED: In combination with ALIGNOF data offsets can be verified.
A more general version of the IS_ALIGNED macro previously defined by several modules.

ADDRESS_IS_ALIGNED: Variant of IS_ALIGNED for pointers and addresses.
Replaces module-specific definitions throughout the codebase.

ALIGN_VALUE_ADDEND: The addend to align up can be used to directly
determine the required offset for data alignment.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
---
 MdePkg/Include/Base.h | 90 +++++++++++++++++++-
 1 file changed, 89 insertions(+), 1 deletion(-)

diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
index 2da08b0c787f..32d0e512e05f 100644
--- a/MdePkg/Include/Base.h
+++ b/MdePkg/Include/Base.h
@@ -789,6 +789,35 @@ typedef UINTN  *BASE_LIST;
 #define OFFSET_OF(TYPE, Field) ((UINTN) &(((TYPE *)0)->Field))
 #endif
 
+/**
+  Returns the alignment requirement of a type.
+
+  @param   TYPE  The name of the type to retrieve the alignment requirement of.
+
+  @return  Alignment requirement, in Bytes, of TYPE.
+**/
+#if defined(__GNUC__) || defined(__clang__) || (defined(_MSC_VER) && _MSC_VER >= 1900)
+  //
+  // All supported versions of GCC and Clang, as well as MSVC 2015 and later,
+  // support the standard operator _Alignof.
+  //
+  #define ALIGNOF(TYPE)  _Alignof (TYPE)
+#elif defined(_MSC_VER)
+  //
+  // Earlier versions of MSVC, at least MSVC 2008 and later, support the
+  // vendor-extension __alignof.
+  //
+  #define ALIGNOF(TYPE)  __alignof (TYPE)
+#else
+  //
+  // For compilers that do not support inbuilt alignof operators, use OFFSET_OF.
+  // CHAR8 is known to have both a size and an alignment requirement of 1 Byte.
+  // As such, A must be located exactly at the offset equal to its alignment
+  // requirement.
+  //
+  #define ALIGNOF(TYPE) OFFSET_OF (struct { CHAR8 C; TYPE A; }, A)
+#endif
+
 /**
   Portable definition for compile time assertions.
   Equivalent to C11 static_assert macro from assert.h.
@@ -824,6 +853,21 @@ STATIC_ASSERT (sizeof (CHAR16)  == 2, "sizeof (CHAR16) does not meet UEFI Specif
 STATIC_ASSERT (sizeof (L'A')    == 2, "sizeof (L'A') does not meet UEFI Specification Data Type requirements");
 STATIC_ASSERT (sizeof (L"A")    == 4, "sizeof (L\"A\") does not meet UEFI Specification Data Type requirements");
 
+STATIC_ASSERT (ALIGNOF (BOOLEAN) == sizeof (BOOLEAN), "Alignment of BOOLEAN does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (INT8)    == sizeof (INT8),    "Alignment of INT8 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (UINT8)   == sizeof (UINT8),   "Alignment of INT16 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (INT16)   == sizeof (INT16),   "Alignment of INT16 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (UINT16)  == sizeof (UINT16),  "Alignment of UINT16 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (INT32)   == sizeof (INT32),   "Alignment of INT32 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (UINT32)  == sizeof (UINT32),  "Alignment of UINT32 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (INT64)   == sizeof (INT64),   "Alignment of INT64 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (UINT64)  == sizeof (UINT64),  "Alignment of UINT64 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (CHAR8)   == sizeof (CHAR8),   "Alignment of CHAR8 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (CHAR16)  == sizeof (CHAR16),  "Alignment of CHAR16 does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (INTN)    == sizeof (INTN),    "Alignment of INTN does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (UINTN)   == sizeof (UINTN),   "Alignment of UINTN does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (VOID *)  == sizeof (VOID *),  "Alignment of VOID * does not meet UEFI Specification Data Type requirements");
+
 //
 // The following three enum types are used to verify that the compiler
 // configuration for enum types is compliant with Section 2.3.1 of the
@@ -847,6 +891,10 @@ STATIC_ASSERT (sizeof (__VERIFY_UINT8_ENUM_SIZE) == 4, "Size of enum does not me
 STATIC_ASSERT (sizeof (__VERIFY_UINT16_ENUM_SIZE) == 4, "Size of enum does not meet UEFI Specification Data Type requirements");
 STATIC_ASSERT (sizeof (__VERIFY_UINT32_ENUM_SIZE) == 4, "Size of enum does not meet UEFI Specification Data Type requirements");
 
+STATIC_ASSERT (ALIGNOF (__VERIFY_UINT8_ENUM_SIZE)  == sizeof (__VERIFY_UINT8_ENUM_SIZE),  "Alignment of enum does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (__VERIFY_UINT16_ENUM_SIZE) == sizeof (__VERIFY_UINT16_ENUM_SIZE), "Alignment of enum does not meet UEFI Specification Data Type requirements");
+STATIC_ASSERT (ALIGNOF (__VERIFY_UINT32_ENUM_SIZE) == sizeof (__VERIFY_UINT32_ENUM_SIZE), "Alignment of enum does not meet UEFI Specification Data Type requirements");
+
 /**
   Macro that returns a pointer to the data structure that contains a specified field of
   that data structure.  This is a lightweight method to hide information by placing a
@@ -868,6 +916,46 @@ STATIC_ASSERT (sizeof (__VERIFY_UINT32_ENUM_SIZE) == 4, "Size of enum does not m
 **/
 #define BASE_CR(Record, TYPE, Field)  ((TYPE *) ((CHAR8 *) (Record) - OFFSET_OF (TYPE, Field)))
 
+/**
+  Checks whether a value is a power of two.
+
+  @param   Value  The value to check.
+
+  @return  Whether Value is a power of two.
+**/
+#define IS_POW2(Value)  ((Value) != 0U && ((Value) & ((Value) - 1U)) == 0U)
+
+/**
+  Checks whether a value is aligned by a specified alignment.
+
+  @param   Value      The value to check.
+  @param   Alignment  The alignment boundary used to check against.
+
+  @return  Whether Value is aligned by Alignment.
+**/
+#define IS_ALIGNED(Value, Alignment)  (((Value) & ((Alignment) - 1U)) == 0U)
+
+/**
+  Checks whether a pointer or address is aligned by a specified alignment.
+
+  @param   Address    The pointer or address to check.
+  @param   Alignment  The alignment boundary used to check against.
+
+  @return  Whether Address is aligned by Alignment.
+**/
+#define ADDRESS_IS_ALIGNED(Address, Alignment)  IS_ALIGNED ((UINTN) (Address), Alignment)
+
+/**
+  Determines the addend to add to a value to round it up to the next boundary of
+  a specified alignment.
+
+  @param   Value      The value to round up.
+  @param   Alignment  The alignment boundary used to return the addend.
+
+  @return  Addend to round Value up to alignment boundary Alignment.
+**/
+#define ALIGN_VALUE_ADDEND(Value, Alignment)  (((Alignment) - (Value)) & ((Alignment) - 1U))
+
 /**
   Rounds a value up to the next boundary using a specified alignment.
 
@@ -880,7 +968,7 @@ STATIC_ASSERT (sizeof (__VERIFY_UINT32_ENUM_SIZE) == 4, "Size of enum does not m
   @return  A value up to the next boundary.
 
 **/
-#define ALIGN_VALUE(Value, Alignment) ((Value) + (((Alignment) - (Value)) & ((Alignment) - 1)))
+#define ALIGN_VALUE(Value, Alignment) ((Value) + ALIGN_VALUE_ADDEND (Value, Alignment))
 
 /**
   Adjust a pointer by adding the minimum offset required for it to be aligned on
-- 
2.31.1