JPS59191662A - Detecting system for program runaway - Google Patents

Abstract

PURPOSE:To prevent the breakdown of a program data due to the delay in detecting program runaway by detecting that the program sequence proceeds to a data area, and deciding the program runaway and discontinuing the processing. CONSTITUTION:A program area includes addresses n, n+1-n+k; while a data area includes addresses l, l+1-l+m respectively. An instruction processing circuit 24 gives an access to a main memory 1 via a route (a) to fetch an instruction, and sends the instruction address to a program state display register 22 via a route (b) to execute the instruction. If the program has no conflict through the repetition of above-mentioned procedure, the contents of the register 22 have no value other than n-n+k. While data areas l-l+m are previously written to an ROM for a data area register 21. An address checking circuit 23 compares the contents between registers 21 and 22. Then the operation of the circuit 24 is stopped via a route (f) when a program execution address detects the inside of the data area. Then the program runaway is displayed to the outside via a route (g).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a program runaway detection system in a central processing unit using an accumulated program control system.

The program in the storage program control system is a collection of commands tv for the central processing unit, and the combination of these commands causes the central processing unit to perform various operations. Accordingly,
The normality check of the program was performed by checking the normality of the combination and 71-re, and conventionally using a failure detection timer method.

This fault detection timer-f73 method is a method in which the designer incorporates logic to periodically clear a hard timer when creating a program, and when the hard timer overflows, it is determined that the program has run out of control.

However, this method has the disadvantage that most of the programs and data are destroyed because it takes time for the runaway to be detected after the program runs out of control.

Similarly, if an attempt was made to set the overflow time short in order to shorten the detection time, there was a risk that a runaway would be mistakenly determined when the load increased and the processing time simply increased.

The present invention has been made in view of the above-mentioned conventional circumstances.
Therefore, an object of the present invention is to utilize the program runaway mechanism to detect runaway at an early stage and interrupt processing, in order to prevent program data from being destroyed due to a delay in detecting runaway, which is a drawback of the failure detection timer method. As a result, it is an object of the present invention to provide a new program runaway detection power formula that allows easy cause search and system restart.

In order to achieve the above object, the program runaway detection system according to the present invention installs a first register constituted by a ROM whose contents cannot be changed by software in the central processing unit of the storage program control system. Information on the data area of the memory is set in the first register, and the contents of the second register and the above data area information are displayed to display only the address of instruction 7, among the memory accesses performed during program execution. It is configured to constantly compare the contents of the first register storing the above, and if they match, it is determined that the program has runaway. Destruction prevention is achieved.

A runaway program itself occurs due to a logical contradiction caused by a bug, but program and data corruption occurs when the program progresses to the data area due to the influence of the bug, interpreting simple data as a command and executing it. In most cases, contradictions lead to contradictions, leading to destruction in a snowballing manner. Therefore, a program runaway detection formula can be obtained that detects that the program sequence has proceeded to the data area, determines that program runaway has occurred at the time of detection, and interrupts processing to prevent program and data destruction.

Note that checking that the block sequence has proceeded to the data area is done by setting the address of the currently executing instruction in the data area register, which is made up of the program status display register and ROM and cannot be changed by the program, in advance. This is done by comparing the data area information.

Next, a preferred embodiment of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, reference number 1 indicates a main storage device, and reference number 2 indicates a central processing unit. Reference number In in main memory 1
, In+z, In+ each k n %n+x,
The instruction stored at address n+ is p, DI%f)l
+z.

f) l+m is data stored at addresses l, l+l, and l+m. Therefore, in this embodiment, from address n to n+
The area up to address 1 is the program area, and the area from address 1 to l+m is the data area.

In the central processing unit 2, 21 is a data area register constituted by I'[M and storing data area information;
22 is a program status display register that stores the address of the instruction currently being executed; 23 is an address check circuit that compares the contents of the data area register 21 with the contents of the program status display register 22; Each shows an instruction processing circuit that executes the instruction. a-f
is a route aid indicating the flow of commands or signals.

The program runaway detection procedure according to the present invention is as follows.

The instruction processing circuit 24 accesses the main storage device 1 via route a, loads the instruction, and at the same time sends the instruction address to the program status display register 22 via route b to execute the instruction. When one instruction is completed, the next instruction is repeated one after another, but if there is no contradiction in the program, the contents of the program status display register 22 will never be any other than the value from n to n+, which is the program area.

- The data area register 21 is set in advance by writing data area information (1 to l+m in this embodiment) into the ROM. Area register 2
1 and the contents of the program status display register 22,
It is determined whether the program execution address is within the data area address or not, and if it is within the data area, the instruction processing circuit 24 is stopped using route f, and at the same time, program runaway is indicated to the outside via route g.

As described above, the present invention detects that the execution address of the program has become the data area, determines that the program has runaway, and stops the instruction processing circuit, so that the data in the data area is interpreted as an instruction. It is possible to prevent programs and data from being destroyed by execution. Therefore, according to the present invention, it is possible to search for the cause and restart the system quickly.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1... Main memory, n, n+x, n+, l,
l+x, 1+ml@@address in main memory, In, I
n+x, 60. to In+. Command, Dl, Dl+x
, Dl+m * * * data, 2. fist - central processing unit, 21... data area register, 22. e. program status display register, ku... address check circuit, 24... instruction processing circuit, """g... Auxiliary display indicating the flow of data or signals Patent applicant: NEC Corporation Representative Patent attorney Yutabe Kumagai 7-

Claims (1)

[Claims] In the central processing unit of the storage program control system, a first register consisting of a ROM whose contents cannot be changed by software is installed, information on the data area of the memory is set in the first register, and the program is executed. The contents of the second register, which displays only the address of the instruction fetch among the memory accesses performed in , and the contents of the first register, which stores the data area information, are always compared, and if they match, A program runaway detection formula that is characterized by determining program runaway.