arm64/mm: Validate hotplug range before creating linear mapping

During memory hotplug process, the linear mapping should not be created for
a given memory range if that would fall outside the maximum allowed linear
range. Else it might cause memory corruption in the kernel virtual space.

Maximum linear mapping region is [PAGE_OFFSET..(PAGE_END -1)] accommodating
both its ends but excluding PAGE_END. Max physical range that can be mapped
inside this linear mapping range, must also be derived from its end points.

This ensures that arch_add_memory() validates memory hot add range for its
potential linear mapping requirements, before creating it with
__create_pgd_mapping().

Fixes: 4ab215061554 ("arm64: Add memory hotplug support")
Signed-off-by: Anshuman Khandual <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Steven Price <[email protected]>
Cc: Robin Murphy <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

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