linux-kernel - Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY

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]

Date:	Tue, 29 Sep 2015 18:16:19 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Mark Rutland <mark.rutland@....com>,
	Mark Salter <msalter@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>
Subject: Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions

On Tue, Sep 29, 2015 at 6:03 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 09/27/2015 12:06 AM, Ingo Molnar wrote:
>>
>> * Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
>>
>>>> If we allocate the EFI runtime as a single virtual memory block then issues
>>>> like rounding between sections does not even come up as a problem: we map the
>>>> original offsets and sizes byte by byte.
>>>
>>> Well, by that reasoning, we should not call SetVirtualAddressMap() in the first
>>> place, and just use the 1:1 mapping UEFI uses natively. This is more than
>>> feasible on arm64, and I actually fought hard against using
>>> SetVirtualAddressMap() at all, but I was overruled by others. I think this is
>>> also trivially possible on X64, since the 1:1 mapping is already active
>>> alongside the VA mapping.
>>
>> Could we please re-list all the arguments pro and contra of 1:1 physical mappings,
>> in a post that also explains the background so that more people can chime in, not
>> just people versed in EFI internals? It's very much possible that a bad decision
>> was made.
>>
>
> Pro: by far the sanest way to map the UEFI tables.
> Con: doesn't actually work (breaks on several known platforms.)

Can we at least do 1:1 without an offset on arm64?  Given that Linux
seems to be more of a reference on arm64 than Windows is, maybe that
would give everyone something vaguely sane to work with.

--Andy
--
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/