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Date: Mon, 6 Apr 2020 13:20:42 +0200 From: Borislav Petkov <bp@...en8.de> To: Ard Biesheuvel <ardb@...nel.org> Cc: Arvind Sankar <nivedita@...m.mit.edu>, Sergey Shatunov <me@...k.pw>, hpa@...or.com, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, mingo@...hat.com, Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org, linux-efi <linux-efi@...r.kernel.org>, initramfs@...r.kernel.org, Donovan Tremura <neurognostic@...tonmail.ch>, Harald Hoyer <harald@...er.xyz> Subject: Re: [PATCH 1/2] x86/boot/compressed/64: Remove .bss/.pgtable from bzImage On Mon, Apr 06, 2020 at 11:11:21AM +0200, Ard Biesheuvel wrote: > Yes, it is in the PE/COFF specification. [0] > > The whole problem is that we are conflating 'loading a PE/COFF image' > with 'copying a PE/COFF image into memory', which are not the same > thing. It is not just the layout issue, we are running into other > problems with things like UEFI secure boot and TPM-based measured > boot, where the fact that omitting the standard LoadImage() boot > service (which takes care of these things under the hood) means that > you now have to do your own checks and measurements. These things are > literally all over the place at the moment, shim, GRUB, systemd-boot > etc, with no authoritative spec that describes which component should > be doing what. Sounds to me like what LoadImage() does is what the authoritative spec should be. Perhaps we should write it down as "Do what LoadImage() does... " and then enumerate the requirements. > Commit ec93fc371f014a6fb483e3556061ecad4b40735c has the background, but ... Nice, I like the aspect of letting firmware do only a minimum amount of work. :) > ... I'll look into updating the documentation as well. Thanks! > Note that this stuff is hot off the press, so there may be some issues > lurking (like this one) that we hadn't thought of yet. Right. > Actually, it may be sufficient to #define __efistub_global to > __section(.data) like we already do for ARM, to ensure that these > global flags are always initialized correctly. (I'll wait for Sergey > to confirm that the spurious enabling of the PCI DMA protection > resulting from this BSS issue is causing the boot regression) Cool, but let's not jinx it. :-) Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
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