[PATCH 0/4] objtool: Fixes

[Peter Zijlstra]

Fix various objtool whinges:

  lib/strnlen_user.o: warning: objtool: strnlen_user()+0x33: call to do_strnlen_user() with UACCESS enabled
  lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x33: call to do_strncpy_from_user() with UACCESS enabled

  vmlinux.o: warning: objtool: pvh_start_xen()+0x0: unreachable
  vmlinux.o: warning: objtool: start_secondary()+0x10e: unreachable
  vmlinux.o: warning: objtool: asm_exc_xen_unknown_trap()+0x16: unreachable instruction