[RFC PATCH] arm64: use non-global mappings for UEFI runtime regions

Catalin Marinas catalin.marinas at arm.com
Wed Nov 18 01:43:04 PST 2015

On Tue, Nov 17, 2015 at 09:53:31AM +0100, Ard Biesheuvel wrote:
> As pointed out by Russell King in response to the proposed ARM version
> of this code, the sequence to switch between the UEFI runtime mapping
> and current's actual userland mapping (and vice versa) is potentially
> unsafe, since it leaves a time window between the switch to the new
> page tables and the TLB flush where speculative accesses may hit on
> stale global TLB entries.
> So instead, use non-global mappings, and perform the switch via the
> ordinary ASID-aware context switch routines.
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  arch/arm64/include/asm/mmu_context.h |  2 +-
>  arch/arm64/kernel/efi.c              | 14 +++++---------
>  2 files changed, 6 insertions(+), 10 deletions(-)

Patch applied. Thanks.


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