From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217])
 by mx.groups.io with SMTP id smtpd.web10.107326.1680627238346396559
 for <devel@edk2.groups.io>;
 Tue, 04 Apr 2023 09:53:58 -0700
Authentication-Results: mx.groups.io;
 dkim=pass header.i=@kernel.org header.s=k20201202 header.b=a8Kmto2g;
 spf=pass (domain: kernel.org, ip: 139.178.84.217, mailfrom: ardb@kernel.org)
Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by dfw.source.kernel.org (Postfix) with ESMTPS id D7C296373B
	for <devel@edk2.groups.io>; Tue,  4 Apr 2023 16:53:57 +0000 (UTC)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFD2AC433A1
	for <devel@edk2.groups.io>; Tue,  4 Apr 2023 16:53:56 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;
	s=k20201202; t=1680627236;
	bh=OuL5066UF8sBrFp2nKYXLjoaJLteDHK/cORgzQtjTWw=;
	h=References:In-Reply-To:From:Date:Subject:To:Cc:From;
	b=a8Kmto2g9n8aeg/nhQ706vxTq2Py3LPJ8X1hMHOdCtq34R/+vZzVcDNJKYcogVuFa
	 /D1TGtJzNfWB4l39z+L/rWK9m3LIPFcPTWhELnvyjS2vhHSAoLSFkMdJCquntYDcWY
	 gq4ii0hg44PXxzG3nb4Mpfmax7qcjXJbJgTpqTjMutY9I/sovueLAqhRhN5iplepdw
	 mvYFGC9s0sevm652omiNTxEUKohaQ24DGRHmz4InSoGQ3fy+Wdz5JEM05CGqhQIpUi
	 sj6lUKAajoc5qgTgvB4grmZGJh3EuJ0DfNg67Ei/sJmI1jiibfFJaaXnbBLdcyOV8v
	 Iv4/0f+WhW4pw==
Received: by mail-lj1-f177.google.com with SMTP id by14so15413489ljb.12
        for <devel@edk2.groups.io>; Tue, 04 Apr 2023 09:53:56 -0700 (PDT)
X-Gm-Message-State: AAQBX9dy3D3cxKAhiTOHfsGmqgSt0alnx3XU1ffNKho/9U/EWSRPMSt6
	EweNlPvIsK2LOlNN2v3FIwe12HP2e8BVsiBUn7Q=
X-Google-Smtp-Source: AKy350YRTy3Ap7VTw1SfWWjUrAr8ukHujFuhYDd5thEH4B2zJW3/cE8O9U2mOwyWliXvGIh0r+wcMui/rCKkkYiComc=
X-Received: by 2002:a05:651c:546:b0:2a2:35dd:4b30 with SMTP id
 q6-20020a05651c054600b002a235dd4b30mr999ljp.3.1680627234760; Tue, 04 Apr 2023
 09:53:54 -0700 (PDT)
MIME-Version: 1.0
References: <CAMj1kXG2zXNdz6G_sVpWNM=nx-WF0Eb=gaUdSZPYyqJwWJ3-fg@mail.gmail.com>
 <9C4C1527-1DA6-4DA7-AE98-F2BCA59E2089@posteo.de>
In-Reply-To: <9C4C1527-1DA6-4DA7-AE98-F2BCA59E2089@posteo.de>
From: "Ard Biesheuvel" <ardb@kernel.org>
Date: Tue, 4 Apr 2023 18:53:43 +0200
X-Gmail-Original-Message-ID: <CAMj1kXF9=mN1cLUL8Pc0mewLXk5hk4VvudygmzWO7grwd-2W3A@mail.gmail.com>
Message-ID: <CAMj1kXF9=mN1cLUL8Pc0mewLXk5hk4VvudygmzWO7grwd-2W3A@mail.gmail.com>
Subject: Re: [PATCH v3 0/4] Enable BTI support in memory attributes table
To: =?UTF-8?Q?Marvin_H=C3=A4user?= <mhaeuser@posteo.de>
Cc: devel@edk2.groups.io, Michael Kinney <michael.d.kinney@intel.com>, 
	Liming Gao <gaoliming@byosoft.com.cn>, Jiewen Yao <jiewen.yao@intel.com>, 
	Michael Kubacki <Michael.Kubacki@microsoft.com>, Sean Brogan <sean.brogan@microsoft.com>, 
	Rebecca Cran <quic_rcran@quicinc.com>, Leif Lindholm <quic_llindhol@quicinc.com>, 
	Sami Mujawar <sami.mujawar@arm.com>, Taylor Beebe <t@taylorbeebe.com>, 
	Bob Feng <bob.c.feng@intel.com>, Oliver Smith-Denny <osde@linux.microsoft.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Tue, 4 Apr 2023 at 18:42, Marvin H=C3=A4user <mhaeuser@posteo.de> wrote:
>
>
> > On 4. Apr 2023, at 18:29, Ard Biesheuvel <ardb@kernel.org> wrote:
> > =EF=BB=BFOn Tue, 4 Apr 2023 at 18:19, Marvin H=C3=A4user <mhaeuser@post=
eo.de> wrote:
> >>
> >> FWIW, Reviewed-by: Marvin H=C3=A4user <mhaeuser@posteo.de>
> >>
> >> An off-topic remark, but I find it ominous that when adding a hack lik=
e the DllCharacteristicsEx debug entry, the opportunity is not used to turn=
 it into something that can be expanded in the future without introducing y=
et another hack like this (I know 31 more Bits look plenty now, but if an a=
ddress, offset, or size will be needed=E2=80=A6 ouch).
> >
> > It *can* be expanded in the future. The debug directory entry includes
> > a size field, and once flags get defined that are not present, they
> > just default to unset.
>
> Ugh, I should have known this=E2=80=A6 sorry for my terrible remark! :)
>
> Though doesn=E2=80=99t that mean the size field should ideally be checked=
 in 3/4 (not regarding the extensibility point, but well-formedness of the =
data)?
>

Ideally, yes, we shouldn't read more bytes than the debug entry
describes, and zero out the rest.