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From: =?UTF-8?B?TWFydmluIEjDpHVzZXI=?= <mhaeuser@posteo.de>
Mime-Version: 1.0 (1.0)
Subject: Re: [edk2-devel] [RFC PATCH 2/3] MdeModulePkg: Enable forward edge CFI in mem attributes table
Date: Fri,  3 Feb 2023 08:34:26 +0000
Message-Id: <078B9F5E-E32C-46F1-B0DC-30C138CAA835@posteo.de>
References: <CAMj1kXEB8Timbe8rCG=tdYqei=uORmExXYV=BxK0_GaPTogaFQ@mail.gmail.com>
Cc: devel@edk2.groups.io
In-Reply-To: <CAMj1kXEB8Timbe8rCG=tdYqei=uORmExXYV=BxK0_GaPTogaFQ@mail.gmail.com>
To: Ard Biesheuvel <ardb@kernel.org>
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Sorry, forgot to ask (and it=E2=80=99s probably obvious), but there is a san=
e tag for ELFs that could be translated to the potential new PE tag, right? =
For both GCC and Clang builds?

> On 3. Feb 2023, at 09:28, Ard Biesheuvel <ardb@kernel.org> wrote:
>=20
> =EF=BB=BFOn Fri, 3 Feb 2023 at 09:25, Marvin H=C3=A4user <mhaeuser@posteo.=
de> wrote:
>>=20
>> Hi Ard,
>>=20
>> Short story: No, TE is not a concern for RT drivers, at least not upstrea=
m [1].
>>=20
>> Long story: Even if a downstream added support for RT relocation itself, T=
E images are loaded misaligned by DxeCore, because it lacks a (terrible) wor=
karound as done in PeiCore [2]. It doesn=E2=80=99t look like anyone tried to=
 use them in DXE at all.
>>=20
>> Best regards,
>> Marvin
>>=20
>> [1] https://github.com/tianocore/edk2/blob/11f0014c0e3046e3762eac420b7600=
91d0cdc063/MdePkg/Library/BasePeCoffLib/BasePeCoff.c#L1759
>>=20
>> [2] https://github.com/tianocore/edk2/blob/11f0014c0e3046e3762eac420b7600=
91d0cdc063/MdeModulePkg/Core/Pei/Image/Image.c#L412
>=20
> Ah thanks for digging that up.
>=20
> So all the more reason to add this to the PE/COFF spec rather than
> anywhere else.