ArmPkg/ArmMmuLib: Avoid splitting block entries if possible

Currently, the ARM MMU page table logic will break down any block entry
that overlaps with the region being mapped, even if the block entry in
question is using the same attributes as the new region.

This means that creating a non-executable mapping inside a region that
is already mapped non-executable at a coarser granularity may trigger a
call to AllocatePages (), which may recurse back into the page table
code to update the attributes on the newly allocated page tables.

Let's avoid this, by preserving the block entry if it already covers the
region being mapped with the correct attributes.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>

0 files changed, 0 insertions, 0 deletions