process_verify_xsavelen
error = process_verify_xsavelen(l, xsavelen);
error = process_verify_xsavelen(l, xsavelen);
error = process_verify_xsavelen(l, xsavelen);
int process_verify_xsavelen(struct lwp *, size_t);
KASSERT(process_verify_xsavelen(l, xsavelen) == 0);