CVE-2023-54167

In the Linux kernel, the following vulnerability has been resolved:

m68k: mm: Move initrd phys_to_virt handling after paging_init()

When booting with an initial ramdisk on platforms where physical memory does not start at address zero (e.g. on Amiga):

initrd: 0ef0602c - 0f800000 Zone ranges: DMA [mem 0x0000000008000000-0x000000f7ffffffff] Normal empty Movable zone start for each node Early memory node ranges node 0: [mem 0x0000000008000000-0x000000000f7fffff] Initmem setup node 0 [mem 0x0000000008000000-0x000000000f7fffff] Unable to handle kernel access at virtual address (ptrval) Oops: 00000000 Modules linked in: PC: [<00201d3c>] memcmp+0x28/0x56

As phys_to_virt() relies on m68k_memoffset and module_fixup(), it must not be called before paging_init(). Hence postpone the phys_to_virt handling for the initial ramdisk until after calling paging_init().

While at it, reduce #ifdef clutter by using IS_ENABLED() instead.