From mboxrd@z Thu Jan  1 00:00:00 1970
From: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Subject: Re: [PATCH v2 11/12] ARM: wire up UEFI init and runtime support
Date: Mon, 16 Nov 2015 19:48:13 +0000
Message-ID: <20151116194812.GJ8644@n2100.arm.linux.org.uk>
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On Mon, Nov 16, 2015 at 08:04:00PM +0100, Ard Biesheuvel wrote:
> OK. So you mean set TTBR to the zero page, perform the TLB flush and
> only then switch to the new page tables?

Not quite.

If you have global mappings below TASK_SIZE, you would need this
sequence when switching either to or from the UEFI page tables:

- switch to another set of page tables which only map kernel space
  with nothing at all in userspace.
- flush the TLB.
- switch to your target page tables.

As I say in response to one of your other patches, it's probably
much easier to avoid any global mappings below TASK_SIZE.

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