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 for Android: free password hash cracker in your pocket

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

Message-ID: <20150929093100.GF30623@dhcp-129-73.nay.redhat.com>
Date:	Tue, 29 Sep 2015 17:31:00 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"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>,
	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 09/27/15 at 12:40pm, Borislav Petkov wrote:
> On Sun, Sep 27, 2015 at 09:06:44AM +0200, Ingo Molnar wrote:
> > 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.
> 
> The main reason why we did the additional, top-down mapping was kexec
> kernel wanting to use UEFI runtime facilities too and the braindead
> design of SetVirtualAddressMap() being callable only once per system
> boot. So we had to have stable mappings which are valid in the kexec-ed
> kernel too.
> 
> But this was long time ago and I most certainly have forgotten all the
> details.
> 
> And now I'm wondering why didn't we do the 1:1 thing and rebuild the
> exact same EFI pagetable in the kexec-ed kernel? Because when we do
> an EFI call, we switch to the special pagetable so why didn't we make
> the kexec-ed kernel rebuild the 1:1 pagetable which it can use for EFI
> calls...
> 
> Hmm, again, I've forgotten a lot of details so I'm sure Matt will come
> in and say "No, you can't do that because..."
> 

http://permalink.gmane.org/gmane.linux.kernel.efi/822

And more replies here:
http://comments.gmane.org/gmane.linux.kernel.efi/820

Thanks
Dave
--
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/