Microprocessor protected against parasitic interrupt signals
First Claim
1. A method for processing an interrupt signal using a microprocessor comprising a central processing unit (CPU), an interrupt controller providing an interrupt request signal to the CPU when the interrupt signal is received by the microprocessor, registers having a context stored therein corresponding to a program being executed by the CPU, and a stack for storing the context while an interrupt is being executed, the method comprising:
- detecting a receipt of the interrupt request signal by the CPU from the interrupt controller;
storing the context from the registers to the stack;
verifying that the interrupt request signal is provided to the CPU from the interrupt controller after storing the context to the stack;
sending an interrupt acknowledge signal and reading and executing a first instruction of an interrupt subroutine using the CPU if the interrupt request signal is provided to the CPU; and
restoring the stored context from the stack to the registers and returning the CPU to an initial state if the interrupt request signal is not provided to the CPU.
1 Assignment
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Accused Products
Abstract
A microprocessor is for detecting an interrupt request during execution of a program, saving contextual data elements of the program being executed, sending an interrupt acknowledge signal, and jumping to an interrupt subroutine if the interrupt request is still present after saving the contextual data. Otherwise, the microprocessor resumes execution of the interrupted program.
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Citations
20 Claims
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1. A method for processing an interrupt signal using a microprocessor comprising a central processing unit (CPU), an interrupt controller providing an interrupt request signal to the CPU when the interrupt signal is received by the microprocessor, registers having a context stored therein corresponding to a program being executed by the CPU, and a stack for storing the context while an interrupt is being executed, the method comprising:
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detecting a receipt of the interrupt request signal by the CPU from the interrupt controller;
storing the context from the registers to the stack;
verifying that the interrupt request signal is provided to the CPU from the interrupt controller after storing the context to the stack;
sending an interrupt acknowledge signal and reading and executing a first instruction of an interrupt subroutine using the CPU if the interrupt request signal is provided to the CPU; and
restoring the stored context from the stack to the registers and returning the CPU to an initial state if the interrupt request signal is not provided to the CPU. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for processing an interrupt request using a microprocessor executing a program, the method comprising:
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detecting the interrupt request;
storing contextual data of the program;
sending an interrupt acknowledge signal;
verifying that the interrupt request is present;
resuming execution of the program if the presence of the interrupt request is not verified; and
switching to an interrupt subroutine if the presence of the interrupt request is verified. - View Dependent Claims (8, 9, 10)
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11. A microprocessor comprising:
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registers having a context stored therein;
a stack for storing the context;
an interrupt controller for providing an interrupt request and an interrupt vector when an interrupt signal is applied to the microprocessor; and
a CPU for receiving the interrupt request and the interrupt vector and, upon detection of the interrupt request storing the context in said stack, verifying that the interrupt request is present after storing the context, sending an interrupt acknowledge signal and reading and executing a first instruction of an interrupt subroutine if the presence of the interrupt request is verified, and restoring the stored context from said stack and returning the microprocessor to an initial state if the presence of the interrupt request is not verified. - View Dependent Claims (12, 13, 14, 15, 16, 18, 19, 20)
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17. A microprocessor comprising:
a central processing unit (CPU) for detecting an interrupt request during execution of a program, storing contextual data of the program being executed, sending an interrupt acknowledge signal and switching to an interrupt subroutine if the interrupt request is present after storing the contextual data, and resuming execution of the program if the interrupt request is not present after storing the contextual data.
Specification