From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail02.groups.io (mail02.groups.io [66.175.222.108]) by spool.mail.gandi.net (Postfix) with ESMTPS id 5F6A6D80047 for ; Mon, 11 Mar 2024 19:34:49 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=oKYUQe32aUJuX//bbzoWTzW+uu3hM7djGeMIGHlQlw0=; c=relaxed/simple; d=groups.io; h=DKIM-Filter:Message-ID:Date:MIME-Version:User-Agent:Subject:From:To:Cc:Reply-To:References:In-Reply-To:Precedence:List-Subscribe:List-Help:Sender:List-Id:Mailing-List:Delivered-To:Resent-Date:List-Unsubscribe-Post:List-Unsubscribe:Content-Language:Content-Type:Content-Transfer-Encoding; s=20240206; t=1710185687; v=1; b=KyC3M17PPnUpPWkIYZuT8q1k3MlTFdeYu0wpTnZ5qALwdJqFP9bljCRazmRfvm5VlBw4qzIl 82GCwobybY3v1zFReRxNsLYsgLC8Lo9lZLdbkglRM1nBR2RTF9NKXJ9fI4Ro4wLa22HcPP54Z/u +ofF4cD5fXhXq0+py5ncDAmmYX8XVkGv87140i39fKXV+bz1GGaZwXg6mAuPwrqYXvOZy9TTck/ yvFxRG3jxGtZ6ouakTBPcsWGjIGdxdm+hpK0uShtImiqulTPVXZ8FhJmYqWRK0ogtyDOy/ppFyu BYOciaVOcYkFtAPJ47jnAdpueRjUCC2e8r6dSQ6EFvKqQ== X-Received: by 127.0.0.2 with SMTP id XGsiYY7687511x052qfMHSzZ; Mon, 11 Mar 2024 12:34:47 -0700 X-Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by mx.groups.io with SMTP id smtpd.web11.2481.1710185686992996147 for ; Mon, 11 Mar 2024 12:34:47 -0700 X-Received: from [10.137.194.171] (unknown [131.107.160.171]) by linux.microsoft.com (Postfix) with ESMTPSA id 6BD6320B74C0; Mon, 11 Mar 2024 12:34:46 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 6BD6320B74C0 Message-ID: Date: Mon, 11 Mar 2024 12:34:46 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [edk2-devel][PATCH v1 1/3] MdeModulePkg: ImagePropertiesRecordLib: Use SectionAlignment for CodeSize From: "Oliver Smith-Denny" To: devel@edk2.groups.io, ardb@kernel.org Cc: Liming Gao , Leif Lindholm , Ard Biesheuvel , Sami Mujawar , Taylor Beebe Reply-To: devel@edk2.groups.io,osde@linux.microsoft.com References: <20240227202721.30070-1-osde@linux.microsoft.com> <20240227202721.30070-2-osde@linux.microsoft.com> <5d95548d-d25f-4306-a271-a2960cc81ccf@linux.microsoft.com> <17B9A63355E03AE5.30946@groups.io> <17B9B0CE1BDDC06B.30946@groups.io> In-Reply-To: <17B9B0CE1BDDC06B.30946@groups.io> Precedence: Bulk List-Subscribe: List-Help: Sender: devel@edk2.groups.io List-Id: Mailing-List: list devel@edk2.groups.io; contact devel+owner@edk2.groups.io Resent-Date: Mon, 11 Mar 2024 12:34:47 -0700 List-Unsubscribe-Post: List-Unsubscribe=One-Click List-Unsubscribe: X-Gm-Message-State: lUGGzngVr2xbASc91hUNtQ1Kx7686176AA= Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-GND-Status: LEGIT Authentication-Results: spool.mail.gandi.net; dkim=pass header.d=groups.io header.s=20240206 header.b=KyC3M17P; spf=pass (spool.mail.gandi.net: domain of bounce@groups.io designates 66.175.222.108 as permitted sender) smtp.mailfrom=bounce@groups.io; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=linux.microsoft.com (policy=none) On 3/4/2024 2:38 PM, Oliver Smith-Denny wrote: > On 3/4/2024 11:24 AM, Oliver Smith-Denny wrote: >> On 3/4/2024 10:54 AM, Ard Biesheuvel wrote: >>> On Mon, 4 Mar 2024 at 18:49, Oliver Smith-Denny >>> wrote: >>>> >>>> Hi Ard, >>>> >>>> On 3/1/2024 3:58 AM, Ard Biesheuvel wrote: >>>>> Hi Oliver, >>>>> >>>>> On Tue, 27 Feb 2024 at 21:27, Oliver Smith-Denny >>>>> wrote: >>>>>> >>>>>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ImageRecordCodeSection->CodeSegmentS= ize =3D=20 >>>>>> Section[Index].SizeOfRawData; >>>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ImageRecordCodeSection->CodeSegmentS= ize =3D ALIGN_VALUE=20 >>>>>> (Section[Index].SizeOfRawData, SectionAlignment); >>>>>> >>>>> >>>>> This should be the virtual size, not the file size, right? >>>> >>>> Correct, SectionAlignment is the alignment of the image as loaded in >>>> memory, so in the case of a DXE runtime driver on ARM64, it will be >>>> 64k. >>>> >>> >>> No, I mean we should not be using SizeOfRawData here but VirtualSize. >>> >>> I understand this is unlikely to make a difference in practice, but >>> VirtualSize may exceed SizeOfRawData by a wide margin, and we need the >>> whole region to be covered. >>> >> >> I see, yes I do believe VirtualSize could be used here instead. Two >> things give me pause. One is that the PE spec states that SizeOfRawData >> is rounded and VirtualSize is not, so that SizeOfRawData may be greater >> than the VirtualSize in some cases (which seems incorrect). >> >> The other is that the image loader partially uses VirtualSize when >> loading: >> >> https://github.com/tianocore/edk2/blob/918288ab5a7c3abe9c58d576ccc0ae32e= 2c7dea0/MdePkg/Library/BasePeCoffLib/BasePeCoff.c#L1399-L1400 >> >> However, when determining the size of a loaded image (and therefore the >> number of pages to allocate) it will allocate an extra page: >> >> https://github.com/tianocore/edk2/blob/918288ab5a7c3abe9c58d576ccc0ae32e= 2c7dea0/MdeModulePkg/Core/Dxe/Image/Image.c#L646-L652 >> >> as ImageSize here is: >> >> https://github.com/tianocore/edk2/blob/918288ab5a7c3abe9c58d576ccc0ae32e= 2c7dea0/MdePkg/Library/BasePeCoffLib/BasePeCoff.c#L312 >> >> Which according to the spec, SizeOfImage is the size of the image as >> loaded into memory and must be a multiple of section alignment. >> >> So, reflecting on this, let me test with VirtualSize here, I think >> that is the right value to use, the only time we would have a >> SizeOfRawData that is greater than the VirtualSize would be if our >> FileAlignment is greater than our SectionAlignment, which would be >> a misconfiguration. >> >> I do think the ImageLoader should also be fixed to only allocate >> ImageSize number of pages (which should be the sum of the section >> VirtualSizes + any headers that aren't included). Might as well not >> waste an extra page for each image and then our image record code is >> simpler as well (ensuring we are protecting the right pages). >> >> I think this patch series should go in, as it is fixing an active bug, >> but I will also take a look at the image loader creating the image >> records and having a protocol it produces to retrieve the list, to >> attempt to avoid issues like this in the future. >> >=20 > Surprisingly, I am seeing that the VirtualSize is not 64k aligned there. > I am looking deeper into GenFw to make sure it is correctly getting set > to align to SectionAlignment in the section headers. When I use dumpbin > to dump the headers, it shows each section having VirtualSize as 64k > aligned for a runtime image, but the same image doesn't show that in FW. >=20 > I'll do some digging here. >=20 Following up on this: Not surprisingly, different toolchains do different things here. gcc obviously creates ELF files and ElfConvert*.c converts these to PE images. However, when it does this, it always sets the section and file alignment to the same value (I'm not as familiar with ELF images, I'm not sure if there is the same concept as file vs section alignment). GenFw could probably update this information to shrink the file alignment, but that's a space optimization for gcc built binaries. In ElfConvert.c, the VirtualSize does get set to the section aligned value, which is what I would expect from the spec. In MSVC PE images, VirtualSize is not section aligned and the expectation appears to be that loaders will align the VirtualSize to the section alignment. I am planning on reaching out to the MSVC folks to learn why this is the case, is it intended, etc., as my understanding is that the VirtualSize in the section headers should be section aligned. We are stuck with this for existing MSVC toolchains, however, so we will need to align either the VirtualSize or SizeOfRawData to the section alignment when we create the image records. I don't have a preference between the two, they end up being the same when we align them, so I can send a v2 with aligning the VirtualSize. This will be a no-op on gcc built binaries and will set it to the correct value for MSVC. Thanks, Oliver -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#116653): https://edk2.groups.io/g/devel/message/116653 Mute This Topic: https://groups.io/mt/104610770/7686176 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io] -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-