arm64: head.S: ensure idmap_t0sz is visible
arm64: head.S: ensure idmap_t0sz is visible

We write idmap_t0sz with SCTLR_EL1.{C,M} clear, but we only have the
guarnatee that the kernel Image is clean, not invalid in the caches, and
therefore we might read a stale value once the MMU is enabled.

This patch ensures we invalidate the corresponding cacheline after the
write as we do for all other data written before we set SCTLR_EL1.{C.M},
guaranteeing that the value will be visible later. We rely on the DSBs
in __create_page_tables to complete the maintenance.

Signed-off-by: Mark Rutland <1db9dd262beaa64f35756dd39531d9747b7778bb@arm.com>
CC: Catalin Marinas <15ce75b290ebaf27c3f9fd73ab848685ed3d8261@arm.com>
Cc: Will Deacon <b913f13ef92ac157955c954ccaaff7be065faba4@arm.com>
Signed-off-by: Will Deacon <b913f13ef92ac157955c954ccaaff7be065faba4@arm.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs