linux-kernel - Re: [PATCH 1/2] x86/efi: Map EFI memmap entries in-order at runtime

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <F1F37F57-7D03-4FC2-955E-7E8C82540A24@zytor.com>
Date:	Sat, 26 Sep 2015 13:19:15 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Fleming <matt@...eblueprint.co.uk>
CC:	Andy Lutomirski <luto@...capital.net>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Matt Fleming <matt.fleming@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"Lee, Chun-Yi" <jlee@...e.com>, Borislav Petkov <bp@...e.de>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Peter Jones <pjones@...hat.com>,
	James Bottomley <JBottomley@...n.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Dave Young <dyoung@...hat.com>,
	stable <stable@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] x86/efi: Map EFI memmap entries in-order at runtime

Sadly a lot of firmware is known to fail in that configuration :(  That was very much our guest choice.

I don't actually think it is all that infeasible to keep relative offsets consistent for the regions we have to map. PMD_SIZE is not a very large chunk so it could be a problem.

On September 26, 2015 1:09:17 PM PDT, Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
>
>> On 26 sep. 2015, at 12:57, Matt Fleming <matt@...eblueprint.co.uk>
>wrote:
>> 
>>> On Sat, 26 Sep, at 12:49:26PM, H. Peter Anvin wrote:
>>> 
>>> It is still a hack unless all relative offsets are preserved.  That
>>> is actually simpler, even: no sorting necessary.
>> 
>> Unless I'm missing something, preserving relative offsets is exactly
>> what we do today, modulo PMD_SIZE gaps.
>> 
>
>I think what Peter means is preserving the relative offsets inside the
>entire 1:1 space.
>
>This is not at all what we do currently, and i don't think it is
>generally feasible on 32-bit (since the physical range may conflict
>with the virtual kernel mappings)
>
>However, on 64 bit (both arm and x86), this boils down to not calling
>setVA() in the first place, which i'm all in favor of.

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/