useracc
if (!useracc((void *)addr, size, VM_PROT_READ)) {
(!useracc(__DECONST(caddr_t, uaddr), size, VM_PROT_READ))
#define access_ok(prot, p, l) useracc((p), (l), (prot))
if (!useracc(req->error, req->lerror, VM_PROT_WRITE))
bool useracc(void *, int, int);