This thesis addresses the critical need for robust validation of emerging architectural features, with a particular focus on the Guarded Control Stack (GCS) introduced in the Arm Architecture 64-bit (AArch64). GCS is a key security enhancement aimed at strengthening Control-Flow Integrity (CFI) by using hardware-based mechanisms to prevent control-flow hijacking attacks. As modern processors grow increasingly complex, and the consequences of security flaws become more severe, there is a pressing need for validation methodologies that are both thorough and strictly aligned with architectural specifications. To address this challenge, the thesis presents a coverage-driven validation methodology specifically tailored to GCS. The main contribution of this work is the creation and integration of a dedicated sequence into an existing architectural coverage model, targeting the Guarded Control Stack feature.