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US 10,540,299 B2Granted
Resetting operating state holding element
AssigneeArm Limited
InventorsCarlo Dario Fanara, Frederic Jean Denis Arsanto, Guillaume Schon, Jocelyn Francois Orion Jaubert
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Abstract
An apparatus has processing circuitry to perform data processing in one of two or more operating states associated with different levels of privilege. At least one operating state holding element holds a state indication indicating a current operating state of the processing circuitry. In response to a transition of a reset signal from a first value to a second value for triggering a reset of the processing circuitry, the at least one operating state holding element resets the state indication to indicate a default operating state other than a most privileged operating state of the two or more operating states.
Claims12
An apparatus comprising:
- processing circuitry to perform data processing in one of a plurality of operating states associated with different levels of privilege;
- and
- at least one operating state storage circuit to hold a state indication indicating a current operating state of the processing circuitry;
- a reset tree to distribute a reset signal received at a root node of the reset tree to reset signal inputs of a plurality of data storage circuits including said at least one operating state storage circuit, each data storage circuit to reset a data value held by the data storage circuit to a respective reset value in response to a transition of a reset signal from a first value to a second value for triggering a reset of the processing circuitry;
- wherein in response to the transition of the reset signal at an intermediate node of the reset tree from the first value to the second value, said at least one operating state storage circuit is configured to reset the state indication to indicate a default operating state other than a most privileged operating state of said plurality of operating states;
- and
- state updating circuitry to update said at least one operating state storage circuit to indicate a more privileged operating state than the default operating state, in response to a transition of the reset signal received at the root node of the reset tree from the second value to the first value.
4 more elements
An apparatus comprising:
- means for performing data processing in one of a plurality of operating states associated with different levels of privilege;
- and
- at least one means for holding a state indication indicating a current operating state of the means for performing data processing;
- and
- means for distributing a reset signal received at a root node to reset signal inputs of a plurality of means for holding data including said at least one means for holding the state indication, each means for holding data to reset a data value held by the means for holding data to a respective reset value in response to a transition of the reset signal from a first value to a second value for triggering a reset of the means for performing data processing;
- wherein in response to the transition of the reset signal at an intermediate node of the means for distributing from the first value to the second value, said at least one means for holding is configured to reset the state indication to indicate a default operating state other than a most privileged operating state of said plurality of operating states;
- and
- means for updating said at least one means for holding the state indication to indicate a more privileged operating state than the default operating state, in response to a transition of the reset signal received at the root node from the second value to the first value.
5 more elements
A data processing method comprising:
- performing data processing using processing circuitry in one of a plurality of operating states associated with different levels of privilege;
- holding a state indication indicating a current operating state of the processing circuitry in at least one operating state storage circuit;
- and
- distributing a reset signal received at a root node of a reset tree to reset signal inputs of a plurality of data storage circuits including said at least one operating state storage circuit, each data storage circuit resetting a data value held by the data storage circuit to a respective reset value in response to a transition of the reset signal from a first value to a second value for triggering a reset of the processing circuitry;
- in response to the transition of the reset signal at an intermediate node of the reset tree from the first value to the second value, resetting the state indication held by said at least one operating state storage circuit to indicate a default operating state other than a most privileged operating state of said plurality of operating states;
- and
- in response to a transition of the reset signal received at the root node of the reset tree from the second value to the first value, updating said at least one operating state storage circuit to indicate a more privileged operating state than the default operating state.
4 more elements
Dependencies are inferred from the claim text.