arm64: use non-global mappings for UEFI runtime regions

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 <[email protected]>
Acked-by: Will Deacon <[email protected]>
Reviewed-by: Mark Rutland <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>

0 files changed, 0 insertions, 0 deletions