Re: [PATCH 3/5] MdePkg/Base.h: Introduce various alignment-related macros

["Michael D Kinney" <michael.d.kinney@intel.com>]

Hi Gerd,

A few comments included below.

Thanks,

Mike

> -----Original Message-----
> From: Gerd Hoffmann <kraxel@redhat.com>
> Sent: Thursday, March 2, 2023 10:51 PM
> To: devel@edk2.groups.io
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>; Gerd Hoffmann <kraxel@redhat.com>; Wang, Jian J <jian.j.wang@intel.com>; Yao,
> Jiewen <jiewen.yao@intel.com>; Marvin Häuser <mhaeuser@posteo.de>; James Bottomley <jejb@linux.ibm.com>; Michael Roth
> <michael.roth@amd.com>; Wu, Hao A <hao.a.wu@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Oliver Steffen
> <osteffen@redhat.com>; Xu, Min M <min.m.xu@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>; Ni, Ray <ray.ni@intel.com>; Tom
> Lendacky <thomas.lendacky@amd.com>; Aktas, Erdem <erdemaktas@google.com>; Liu, Zhiguang <zhiguang.liu@intel.com>; Pawel Polawski
> <ppolawsk@redhat.com>; Justen, Jordan L <jordan.l.justen@intel.com>; Vitaly Cheptsov <vit9696@protonmail.com>
> Subject: [PATCH 3/5] MdePkg/Base.h: Introduce various alignment-related macros
> 
> From: 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 | 95 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 94 insertions(+), 1 deletion(-)
> 
> diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
> index d209e6de280a..2053314b50d1 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_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");

This will need to be merged with latest edk2 because of change from UINT32 to INT32 for the 32-bit size checks

> +
>  /**
>    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 +890,46 @@ 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.

Change to @retval TRUE and @retval FALSE descriptions



> +**/
> +#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.

Change to @retval TRUE and @retval FALSE descriptions

> +**/
> +#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.


Change to @retval TRUE and @retval FALSE descriptions

> +**/
> +#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.

Determines the minimum number of bytes 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.

Minimum number of bytes to add to Value to reach the next alignment boundary specified by 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 +942,7 @@ 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
> --
> 2.39.2