System for protecting sensitive data from user code in register window architecture
AssigneeSilverbrook Research Pty Ltd
InventorsDavid William Funk, Barry Gauke, Kia Silverbrook
Life of this patent
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Abstract
A system for protecting supervisor mode data from user code in a register window architecture of a processor is provided. The system, when transitioning from supervisor mode to user mode, setting at least one invalid window bit in the invalid window mask of the architecture additional to the invalid window bit set for the reserved window of the invalid window mask. The additional bit is set for a transition window between supervisor and user data windows.
Claims15
A system for protecting supervisor mode data from user code, the system comprising a processor which implements a register window architecture supporting supervisor and user modes, the processor being configured to implement the architecture as separate window stacks for the supervisor and user modes with a transition window in one of the window stacks set with at least one invalid window bit in an invalid window mask of the architecture additional to an invalid window bit set for a reserved window of the invalid window mask for transitioning from the supervisor mode to the user mode,
- wherein the supervisor mode window stack is stored in supervisor mode-only and user mode accessible memory and the user mode window stack is stored in user mode accessible memory, and
- a unique numerical label is assigned to each register window starting from 0 and increasing monotonically for every save.
Dependencies are inferred from the claim text.