The kernel calls these functions on CPU online and hence they must not
be marked __init.

Otherwise if the memory they occupied has been reused the system can
crash in various ways. Sachin reported it caused his LPAR to
spontaneously restart with no other output. With xmon enabled it may
drop into xmon with a dump like:

  cpu 0x1: Vector: 700 (Program Check) at [c000000003c5fcb0]
      pc: 00000000011e0a78
      lr: 00000000011c51d4
      sp: c000000003c5ff50
     msr: 8000000000081001
    current = 0xc000000002c12b00
    paca    = 0xc000000003cff280	 irqmask: 0x03	 irq_happened: 0x01
      pid   = 0, comm = swapper/1
  ...
  [c000000003c5ff50] 0000000000087c38 (unreliable)
  [c000000003c5ff70] 000000000003870c
  [c000000003c5ff90] 000000000000d108

Fixes: 3b47b754 ("powerpc/book3s64/kuap: Move KUAP related function outside radix")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
[mpe: Expand change log with details and xmon output]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201214080121.358567-1-aneesh.kumar@linux.ibm.com