forked from Mirrors/opensbi
6966ad0abe
This is achieved by removing the 'no-map' property from the 'reserved-memory' node when PMP is present, otherwise we keep it as it offers a small protection if the OS does not map this region at all. A new callback in platform_override is introduced and allows to fixup the device-tree. It is used here to override this new default behaviour on SiFive Fu540 platforms that has an erratum that prevents S-mode software to access a PMP protected region using 1GB page table mapping. If PMP is present, telling the OS not to map the reserved regions does not add much protection since it only avoids access to regions that are already protected by PMP. But by not allowing the OS to map those regions, it creates holes in the OS system memory map and prevents the use of hugepages which would generate, among other benefits, less TLB miss. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Reviewed-by: Atish Patra <atish.patra@wdc.com> Reviewed-by: Anup Patel <anup.patel@wdc.com>