ARM_PAGE_SHIFT
#define ARM_PAGE_SIZE (1 << ARM_PAGE_SHIFT) /* Page size */
_Static_assert(PAGE_SHIFT == ARM_PAGE_SHIFT, "PAGE_SHIFT mismatch");
pteindex = (va - vm->hdr.kernbase) >> ARM_PAGE_SHIFT;
va = vm->hdr.kernbase + (pteindex << ARM_PAGE_SHIFT);