func (p *Process) findMapping(a Address) *Mapping {
	t3 := p.pageTable[a>>52]
	if t3 == nil {
		return nil
	}
	t2 := t3[a>>42%(1<<10)]
	if t2 == nil {
		return nil
	}
	t1 := t2[a>>32%(1<<10)]
	if t1 == nil {
		return nil
	}
	t0 := t1[a>>22%(1<<10)]
	if t0 == nil {
		return nil
	}
	return t0[a>>12%(1<<10)]
}
func (p *Process) findMapping(a Address) *Mapping {
	t3 := p.pageTable[a>>52]
	if t3 == nil {
		return nil
	}
	t2 := t3[a>>42%(1<<10)]
	if t2 == nil {
		return nil
	}
	t1 := t2[a>>32%(1<<10)]
	if t1 == nil {
		return nil
	}
	t0 := t1[a>>22%(1<<10)]
	if t0 == nil {
		return nil
	}
	return t0[a>>12%(1<<10)]
}
// findMapping is simple enough that it inlines.