JPH02156357A - How to prevent program destruction - Google Patents

Abstract

PURPOSE:To prevent a control program from being destroyed by announcing the step information of the control program, which is just processed, to an operating system in the case of an access prohibition area and interrupting the processing of the control program. CONSTITUTION:An interruption control circuit 2 sends an interrupting signal to a processor 1 and instructs the execution of a program for destruction detection. The processor 1 reads the programs for destruction detection, which is stored to an internal memory, etc., and extracts an address from a RAM access instruction. Then, it is investigated whether the RAM access instruction is a writing instruction or not. When the RAM access instruction is the writing instruction, the processor 1 refers the area of the control program which is developed to a RAM 5. In the case of an accessable area, the processing of the step of the control program, which is just processed, is executed. In the case of the access prohibition area, the step information of the control program to be just processed are informed to the OS and the processing of the control program is interrupted.

Description

[Detailed Description of the Invention] [Summary] Regarding a program destruction prevention method for preventing destruction of a control program on a memory when a processor accesses the memory, prevention of destruction of a control program and causes of incorrect processing by a processor. For the purpose of facilitating investigation, in a device equipped with a processor, a memory, and an access detection means that detects memory access by the processor and sends an interrupt signal, the processor detects the control program by the interrupt signal of the access detection means. A destruction detection program is prepared that branches from processing and executes, and when the access detection means sends an interrupt signal, it extracts the address sent by the processor, checks whether it is a write or not, and if it is a write, the memory reference area is The specified accessible area, write-protected area, and access-prohibited area are referenced, and if the memory area pointed to by the extracted address is an accessible area, the process returns to the control program, and if not, the step being processed is sent to O8. Notify the information, interrupt the processing of the control program, and if it is not a write, refer to the memory reference area, and if the memory area pointed to by the extracted address is an accessible area or a write-protected area, the control program Returning to the processing of step , if the area is an access prohibited area, the O3 is notified of the step information being processed and the processing of the control program is interrupted.

[Industrial application field]

The present invention relates to a device controlled by a processor that operates by reading out a control program developed on a memory, and in particular, the present invention relates to a program destruction device that prevents destruction of the control program on the memory when the processor accesses the memory. Regarding prevention methods.

In recent years, as devices controlled by processors have become more sophisticated and versatile, the control programs that instruct the operations of the processors are required to have high reliability. It is read from the external storage device and developed on the RAM, and the processor
The control program is read by accessing AM.

For this reason, the control program developed on the RAM may be destroyed if the processor accesses the RAM by mistake. In this case, a part of the control program may be destroyed, causing the processor to malfunction or operate unexpectedly by the programmer, causing it to run out of control.

Therefore, if the processor accidentally accesses the RAM, processing is immediately interrupted, the processor is prevented from going out of control, the control program is prevented from being destroyed, and the cause of the processor's erroneous access can be easily investigated. There is a need to.

[Conventional technology]

Conventionally, after the contents of RAM are rewritten and a problem such as a runaway processor occurs, the contents of RAM are dumped.
The control programs and data are inspected to determine the cause of the processor runaway.

[Problem to be solved by the invention]

As mentioned above, conventionally, the cause of a runaway processor is investigated after it has occurred, so control programs are often continuously destroyed due to a runaway processor.
There is a problem in that it is difficult to check the execution contents of the control program when the processor erroneously accesses the RAM, due to timing considerations, and it takes a lot of time to investigate the cause of the processor's malfunction.

In view of these problems, the present invention provides that the processor
The purpose of this system is to immediately interrupt processing in the event of erroneous access to the processor, to prevent the control program from being destroyed continuously, and to facilitate investigation of the cause of the erroneous processor processing.

[Means to solve the problem]

FIG. 1 is a process flowchart showing the configuration of the present invention.

FIG. 1 shows the processing flow of a processor of an apparatus controlled by a processor that reads and operates a control program developed on a memory, and 7 to 1j are processing steps.

[Effect]

A processor that operates based on instructions of a control program expanded on a memory, a memory that expands the control program, and access detection means that detects access by the processor to the memory and sends an interrupt signal to the processor. When the access detection means sends an interrupt signal, the processor of the device equipped with the above extracts the address sent by the processor to the memory in processing step 7.

Then, in processing step 8, it is checked whether the processor has sent a write command to the memory.

If a write command has been sent in processing step 8, in processing step 9, the reference area of the destructive inspection program stored in advance in memory is referenced, and the accessible area and write-inhibited area specified by this reference area are determined. Then, an accessible area for the memory is read from the access prohibited area.

Then, in processing step 10, if the memory area pointed to by the address extracted in processing step 7 points to the accessible area read out in processing step 9, in processing step 11, the control program being processed is Return to step processing execution.

In processing step IO, if the memory area pointed to by the address extracted in processing step 7 does not point to the accessible area read out in processing step 9, that is,
If a write-prohibited area or an access-prohibited area is specified, in processing step 12, step information of the control program that is being processed is notified to the operating system (hereinafter abbreviated as O3). That is, it is notified of which steps of the control program have been processed. Then, in processing step 13, the processing of the control program is interrupted.

If the instruction sent by the processor in processing step 8 is not a write instruction, that is, if it is a read instruction, in processing step 14, the reference area of the destructive inspection program stored in advance in memory is referred to, and this reference area is referenced. An accessible area and a write-inhibited area for the memory are read out of the accessible area, write-inhibited area, and access-inhibited area specified by the area.

Then, in processing step 15, if the memory area pointed to by the address extracted in processing step 7 points to the accessible area or write-protected area read out in processing step 14, then in processing step 11, if the memory area pointed to by the address extracted in processing step 7 Return to execution of the steps in the control program.

In processing step 15, if the memory area pointed to by the address extracted in processing step 7 does not point to an accessible area or an access-prohibited area read out in processing step 14, in other words, it does not point to an access-prohibited area. For example, processing steps 12 and 13 are performed as before.

With the above, it is possible to detect whether or not the address sent by the processor is incorrect, and if it is incorrect, to immediately interrupt the processing of the control program and to notify the O8 of the step information of the control program that was being processed. Become.

Therefore, it is possible to prevent the control program from being destroyed continuously, and to easily investigate the cause of erroneous processing by the processor.

〔Example〕

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a flowchart for explaining the operation of FIG. 2, FIG. 4 is a diagram for explaining the development state of the control program and RAM, and FIG. 5 is a diagram for explaining the destruction detection program reference area.

At the time of initialization, the processor 1 sends an address to the ROM 3 via the address bus, reads out an initialization program via the data bus, and starts operation. Then, the address is sent to the external storage device 4, and the control program and
Data necessary to execute this control program is read.

Then, a write command is sent to the RAM 5 via the control bus, an address is sent to the RAM 5 via the address bus, and the control program and data read from the external storage device 4 via the data bus are transferred to the area corresponding to the address. It is developed and written as shown in FIG.

When the control program is deployed on the RAM 5, there is a common data area that stores data that is commonly used by multiple programs, and a data area that stores data that is used exclusively by each program, that is, a program A month data area. ,
It is divided into a program B monthly data area, a data area for other programs, and an area where each program is stored, that is, a program A storage area, a program B storage area, and another program storage area.

Also, among the data written to the common data area, there is data such as tables that must not be rewritten, and such data is written to the write-protected area and cannot be rewritten, as shown in Figure 4 ■. Good data is written to an accessible area, that is, an area where writing/reading is possible, as shown in FIG.

Similarly, in the program A month data area, as shown in Figure 4 (■), data that must not be rewritten is written in the write-protected area, and data that can be rewritten is written in the accessible area, as shown in Figure 4 (■). be included.

Similarly, in the program B month data area, as shown in Figure 4 (■), data that must not be rewritten is written in the write-protected area, and data that can be rewritten is written in the accessible area, as shown in Figure 4 (■). be included.

Furthermore, as shown in FIG. 4, the programs A and B themselves must not be rewritten, so they are written to the write-protected area.

The area shown in FIG. 4 is the area to which the destruction detection program of the present invention refers, ie, the destruction detection program reference area.

The details of this destruction detection program reference area are as shown in FIG.
The 0 area ■ is a write-protected area as shown in Figure 4 ■, and the RAM5 area ■ is an accessible area as shown in Figure 4 ■. As shown in FIG. 4, this is a write-protected area, and the area (2) of the RAM 5 is an accessible area, as shown in (2) in FIG.

Since area ■ of RAM 5 is a data storage area exclusively for program B, it is an access-prohibited area that program A must not access.
The area ■ of M5 is an area where access is prohibited, the area ■ of RAM5 is a write-protected area as shown in FIG. This is an area that A is prohibited from accessing.

Furthermore, since area (2) of the RAM 5 is a reference area exclusively for the destruction detection program, it is an area that program A is prohibited from accessing.

Similarly, when program B is operating, areas ■, ■, and ■ of RAM5 are write-prohibited areas, ■ and ■ are accessible zn areas, and ■, ■, ■, and ■ are areas that are prohibited from access. .

Further, when programs other than programs A and B are in operation, ■ is a write-prohibited area, ■ is an accessible area, and ■ to ■ are access-prohibited areas.

When the control program is stored in the RAM 5, the processor 1 sends a read command to the RAM 5 via the control bus, sends an address to the RAM 5 via the address bus, and outputs the control program and data to the data bus one after another. perform processing using the data in accordance with the instructions of

The processor 1 sequentially executes each step of the control program as shown in FIG.
When an AM access command is specified, the processor 1 sends a write command or a read command to the RAM 5 via the control bus, and sends an address via the address bus, as described above.

When the access detection circuit 6 detects that the processor 1 has sent an address to the RAM 5 via the address bus,
Upon receiving this notification, the interrupt control circuit 2 notifies the interrupt control circuit 2 via the data bus that the RAM 5 has been accessed by the processor 1, and sends an interrupt signal to the processor 1 to execute the destruction detection program. Instruct.

The processor 1 reads a destruction detection program stored in an internal memory or the like, operates according to the instructions of the destruction detection program, branches from the step shown in FIG. 3 of the control program, and executes the destruction detection program. In order to execute the process, as shown in FIG. 3 @, an address is extracted from the RAM access command instructed in step 3 of FIG. 3. Then, as shown in FIG. 3, it is checked whether the RAM access command is a write command.

If the RAM access command is a write command, the processor 1 refers to the area (2) shown in FIG. 4 of the control program developed in the RAM 5, as shown in (2) in FIG. That is,
Refer to the area shown in FIG. 4 and read out the accessible area.

Then, as shown in Figure 3 (■), it is checked whether @ designates the area (■). That is, if the program A is in operation, check whether the address extracted in FIG. 3 @ indicates the area ■ or area ■ in FIG.
It is checked whether the area (■) or the area (■) in FIG. 5 is indicated.

If it is determined that @ indicates the area of [phase] in Figure 3 ■, it is determined that the RAM access instruction of Figure 3 ■ is normal, and the processor l is Like, 3rd
The RAM access command instructed in the step of Figure 3 is executed, but if it is determined that @ does not indicate the area of [phase], the RAM access command of Figure 3 is determined to be abnormal, As shown in FIG. 3 (■), step information of the control program being executed is notified to O3, and as shown in FIG. 3 (■), the processing of the control program is interrupted.

In other words, which step of the control program has been processed?
Since the O8 is notified and the operation is stopped, it is possible to easily investigate the reason why the address of the write-prohibited area or the access-prohibited area was erroneously sent.

In the step @ in Figure 3, if the RAM access command is not a write command, the processor 1 determines that it is a read command, and as shown in Figure 3 ■, refers to the area ■ in Figure 4, and access is possible. and read the write-protected area.

Then, as shown in Figure 3 (■), it is checked whether @ designates the area (■). That is, if the addresses extracted in Figure 3 @ are when program A is operating, then the areas ■, ■, ■, ■,
It is checked whether any of the areas ①, ②, ②, ②, or ② in FIG. 5 is instructed if program B is running.

If it is determined that @ indicates the area of [phase] in O in FIG.
The RAM access command instructed in the step of Figure ■ is executed, but if it is determined that @ does not specify the area of [phase], the control that was being executed is sent to O8 as shown in Figure 3 ■. The step information of the program is notified, and the processing of the control program is interrupted as shown in FIG. 3 [Phase].

〔Effect of the invention〕

As explained above, in the present invention, when the processor mistakenly accesses the RAM, the process is immediately interrupted and the O8 is notified of the step information processed by the control program, thereby preventing the control program from being destroyed continuously. , it is possible to easily investigate the cause of erroneous processing by the processor.

[Brief explanation of the drawing]

FIG. 1 is a process flowchart showing the configuration of the present invention, FIG. 2 is a block diagram of a circuit showing an embodiment of the invention, and FIG. 3 is a flowchart and diagram explaining the operation of FIG. 2. In the figure, 1 is a processor, 2 is an interrupt control circuit, and 3 is a ROM. 4 is an external storage device, and it is in the state of ``Development of Wholesale Brogelam'', and the thread L! -Figure

Claims (1)

[Scope of Claims] A processor that operates based on instructions of a control program expanded on a memory, a memory that expands the control program, and detects access by the processor to the memory and sends an interrupt signal to the processor. In the processing of a device equipped with an access detection means to send out, a destruction detection program is prepared which the processor branches from a processing step of the control program and executes in response to an interrupt signal sent out by the access detection means; When the access detection means sends an interrupt signal, after extracting the address sent by the processor to the memory (
7) Check whether the access to the memory by the processor is for writing (8), and if it is a write to the memory, the accessible area specified by the reference area of the corruption detection program stored in advance in the memory and the write-prohibited area are checked. Read the accessible area for the memory by referring to the area and the prohibited area (
9) Check whether the memory area pointed to by the extracted address is the accessible area (10), and if it is an accessible area, return to execution of the step of the control program that was being processed (11). ), if the area is a write-protected area or an access-prohibited area, the operating system is notified of the step information of the control program that was being processed (
12) interrupts the processing of the control program (13), and if the processor's access to the memory is not for writing, the memory can be accessed by referring to the reference area of the destruction detection program stored in the memory in advance; Read the area and the write-protected area (14), and check whether the memory area indicated by the extracted address is the accessible area or the write-protected area (15).
If the area is an accessible area or a write-protected area, the process returns to the step of the control program that was being processed (11); if it is an area that is not accessible, the operating system returns the step of the control program that was being processed. Notify the information (12) and interrupt the processing of the control program (13)
) A method for preventing program destruction.