forked from Mirrors/opensbi

- If Smepmp is enabled, the access flags of an entry are determined based on truth table defined in Smepmp. - First PMP entry (index 0) is reserved. - Existing boot PMP entries start from index 1. - Since enabling Smepmp revokes the access privileges of the M-mode software on S/U-mode region, first PMP entry is used to map/unmap the shared memory between M and S/U-mode. This allows a temporary access window for the M-mode software to read/write to S/U-mode memory region. Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com> Reviewed-by: Anup Patel <anup@brainfault.org>