The paper presents some new sliding mode control algorithms for uncertain linear plants. The first class of controllers provide global asymptotic stability of the closed-loop system and allow to adjust a guaranteed convergence time of system trajectories into selected neighborhood of the origin independently on domain of initial system states. The design procedure essentially uses block reduction principles and finite-time attractivity properties for polynomial switching surface. The second class of controllers is meant to guarantee global finite-time stability of the closed-loop system with globally bounded settling-time function. The control design algorithms are presented for both single-input and multi-input systems. Theoretical results are supported by numerical simulations.