-----Original Message-----
From: Gerd Hoffmann <kraxel@...>
Sent: Wednesday, March 22, 2023 12:03 AM
To: devel@edk2.groups.io
Cc: Kinney, Michael D <michael.d.kinney@...>; Aktas, Erdem <erdemaktas@...>; James Bottomley <jejb@...>;
Gao, Liming <gaoliming@...>; Marvin Häuser <mhaeuser@...>; Pawel Polawski <ppolawsk@...>; Michael Roth
<michael.roth@...>; Tom Lendacky <thomas.lendacky@...>; Gerd Hoffmann <kraxel@...>; Yao, Jiewen
<jiewen.yao@...>; Wang, Jian J <jian.j.wang@...>; Ard Biesheuvel <ardb+tianocore@...>; Justen, Jordan L
<jordan.l.justen@...>; Wu, Hao A <hao.a.wu@...>; Liu, Zhiguang <zhiguang.liu@...>; Ni, Ray <ray.ni@...>;
Xu, Min M <min.m.xu@...>; Oliver Steffen <osteffen@...>; Vitaly Cheptsov <vit9696@...>
Subject: [PATCH v2 3/6] MdePkg/Base.h: Introduce various alignment-related macros

From: Marvin Häuser <mhaeuser@...>

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@...>
Cc: Liming Gao <gaoliming@...>
Cc: Zhiguang Liu <zhiguang.liu@...>
Cc: Vitaly Cheptsov <vit9696@...>
Signed-off-by: Marvin Häuser <mhaeuser@...>
Signed-off-by: Gerd Hoffmann <kraxel@...>
---
MdePkg/Include/Base.h | 98 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 97 insertions(+), 1 deletion(-)

diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
index e89c84962ab2..6597e441a6e2 100644
--- a/MdePkg/Include/Base.h
+++ b/MdePkg/Include/Base.h
@@ -758,6 +758,40 @@ 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 (__cplusplus)
+//
+// Standard C++ operator.
+//
+#define ALIGNOF(TYPE) alignof (TYPE)
+#elif 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_EXTENSIONS)
+//
+// 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.
@@ -793,6 +827,21 @@ 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
@@ -816,6 +865,10 @@ 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_INT32_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_INT32_ENUM_SIZE) == sizeof (__VERIFY_INT32_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
@@ -837,6 +890,49 @@ STATIC_ASSERT (sizeof (__VERIFY_INT32_ENUM_SIZE) == 4, "Size of enum does not me
**/
#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.
+
+ @retval TRUE Value is a power of two.
+ @retval FALSE Value is not 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.
+
+ @retval TRUE Value is aligned by Alignment.
+ @retval FALSE Value is not 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.
+
+ @retval TRUE Address is aligned by Alignment.
+ @retval FALSE Address is not 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.

@@ -849,7 +945,7 @@ STATIC_ASSERT (sizeof (__VERIFY_INT32_ENUM_SIZE) == 4, "Size of enum does not me
@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
--
2.39.2