From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [edk2-devel] [PATCH] UefiCpuPkg: Fix CPU stack guard support by aligning GDT buffer
To: Vitaly Cheptsov <cheptsov@ispras.ru>,devel@edk2.groups.io
From: "Vitaly Cheptsov" <vit9696@protonmail.com>
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Date: Mon, 20 Sep 2021 09:15:12 -0700
References: <20210920141347.25161-1-cheptsov@ispras.ru>
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Just to make it clear, this is an immediate solution that is good enough to=
 fix the bug. However, a more proper solution would be to introduce the _Al=
ignas ( https://en.cppreference.com/w/c/language/_Alignas ) concept to EDK =
II. I would suggest the following macro in Base.h:

/**
Enforce custom alignment for a variable definition.
Similar to C11 alignas macro from stdalign.h, except it must be functional =
to support MSVC.

@param =C2=A0Alignment =C2=A0Numeric alignment to require.
**/
#ifdef _MSC_EXTENSIONS
#define ALIGNAS(Alignment) __declspec(align(Alignment))
#else
#define ALIGNAS(Alignment) _Alignas(Alignment)
#endif

If there is no disagreement on this, I can imagine submitting an update aft=
er this patch is merged.

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Just to make it clear, this is an immediate solution that is good enough to=
 fix the bug. However, a more proper solution would be to introduce the <a =
href=3D"https://en.cppreference.com/w/c/language/_Alignas" target=3D"_blank=
" rel=3D"noopener">_Alignas</a> concept to EDK II. I would suggest the foll=
owing macro in Base.h:<br /><br />/**<br />&nbsp; Enforce custom alignment =
for a variable definition.<br />&nbsp;&nbsp;Similar to C11 alignas macro fr=
om stdalign.h, except it must be functional to support MSVC.<br /><br />&nb=
sp; @param &nbsp;Alignment &nbsp;Numeric alignment to require.<br />**/<br =
/>
<div>
<div>#ifdef _MSC_EXTENSIONS</div>
<div>&nbsp; #define ALIGNAS(Alignment) __declspec(align(Alignment))</div>
<div>#else</div>
<div>&nbsp; #define ALIGNAS(Alignment) _Alignas(Alignment)</div>
<div>#endif</div>
</div>
<div><br />If there is no disagreement on this, I can imagine submitting an=
 update after this patch is merged.</div>
<div><br /><br /></div>

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