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US 2018/0024945 A1Published application
Context-based protection system
AssigneeCypress Semiconductor Corporation
InventorsJan-Willem Van de Waerdt, Kai Dieffenbach, Uwe Moslehner, Jens Wagner, Mathias Sedner, Venkat NATARAJAN
Life of this patent
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Abstract
A context-based protection system uses tiered protection structures including master protection units, shared memory protection units, a peripheral protection units to provide security to bus transfer operations between central processing units (CPUs), memory array or portions of arrays, and peripherals.
Claims18
A. system comprising:
- a first central processing unit (CPU) configurable to operate in a plurality of protection contexts;
- and
- at least one peripheral module, the peripheral module accessible by the first CPU when the first CPU is configured in a first protection context of the plurality of protection contexts and inaccessible by the first CPU when the first CPU is configured in a second protection context of the plurality of protection contexts.
A bus infrastructure comprising a plurality of protection structures, the plurality of protection structures comprising:
- a memory protection unit (MPU) assigned to a single bus master, the MPU to differentiate user and privileged accesses from the bus master;
- a shared memory protection unit (SMPU) assigned to a plurality of bus bus masters, the SMPU to differentiate between different protection contexts and to differentiate between secure and non-secure access to a memory;
- and
- a peripheral protection unit (PPU) assigned with a peripheral group, the PPU to differentiate secure and non-secure accesses to the peripheral group.
1 more element
A method for controlling access to peripheral modules, the method comprising:
- comparing a first protection context of a plurality of protection contexts of a central processing unit (CPU) to an allowed protection context of a first peripheral module;
- permitting access to the first peripheral module by the CPU if the first protection context of the CPU matches the allowed protection context of the first peripheral module;
- altering the protection context of the CPU from the first protection context to a second protection context;
- prohibiting access to the first peripheral module by the CPU if the second protection context does not match the allowed protection context of the first peripheral module;
- and
- permitting access to a second peripheral module by the CPU if the second protection context of the CPU matches the allowed protection context of the second peripheral module, wherein the first protection context is different from the second protection context.
3 more elements
Dependencies are inferred from the claim text.