JPH05173889A - System for monitoring memory block - Google Patents

Abstract

PURPOSE:To prevent access where a program exceeds the range of a given memory block in a system where data is transmitted and received between programs through the use of the memory block. CONSTITUTION:A memory block monitoring device 5 which is provided with a memory block monitoring table 6 is provided between CPU 1 and a memory 9. A virtual address received from CPU 1 is checked through the use of the memory block monitoring table 6 so that access to the outside of the range of the memory block is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to allocation of a memory block mainly used as a common resource in a real-time system or the like, and more particularly to a method of monitoring access beyond the allocated range of the memory block.

[0002]

2. Description of the Related Art Conventionally, whether or not each memory block is in use is managed by an operating system (OS). However, it was not monitored because the memory access beyond the memory block range by the program cannot be detected.

[0003]

The problem to be solved is that the memory blocks are allocated to consecutive memory areas. Therefore, if a program writes data beyond the range of the memory blocks, the other memory blocks will be deleted. The point is to destroy the contents of. Therefore, the normal operation of the program using the destroyed memory block cannot be guaranteed. In other words, the problem is that erroneous processing of one program causes erroneous processing of another program.

[0004]

A memory block monitoring device having a memory block monitoring table composed of a real address of a memory block head and a block size is provided between a CPU and a memory. In the memory block monitoring device, a virtual address composed of an address identifier, a control bit, a memory block number, and an offset input from the CPU is converted into a real address using the memory block monitoring table, and this address is converted. It is characterized by monitoring whether or not the virtual address is within the range of the memory block during the conversion.

[0005]

Embodiments of the present invention will now be described with reference to the drawings. First, an outline will be described. FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In FIG. 1, 1 is a CPU, 2 is a data bus, 3 is an address bus, 4 is an interrupt line, 5 is a memory block monitoring device, 6 is a memory block monitoring table, 7 is a data bus, 8 is an address bus, and 9 is a memory. Is. FIG. 2 is a configuration diagram of a memory block monitoring table inside the memory block monitoring device 5 shown in FIG. In FIG. 2, reference numeral 20 is the start real address of the memory block (N), and 21 is the memory block (N).
, 22 is the head real address of the memory block (N + 1), and 23 is the size of the memory block (N + 1). FIG. 3 is a configuration diagram of virtual addresses passed from the CPU 1 to the memory block monitoring device 5. In FIG. 3, 30
Is an address identifier, 31 is a block number, 32 is a control bit, and 33 is an offset.

In FIG. 1, the CPU 1 is an address bus 3
The virtual address shown in FIG. 3 is passed to the memory block monitoring device 5 through. The memory block monitoring device 5 uses the memory block monitoring table 6 to check the given virtual address. If the value is normal, the virtual address is converted into a real address and the memory 9 is accessed through the address bus 8. When the value of the virtual address cannot be converted into the real address, the fact is notified to the CPU through the interrupt line 4.

FIG. 4 is an explanatory diagram showing an example of memory block allocation in the memory 9. FIG. 5 is an explanatory diagram showing a configuration example of the memory block monitoring table 6 when the memory blocks are allocated as shown in FIG. FIG. 6 is an explanatory diagram showing an example of conversion from a virtual address to a real address. Here, the operation of the memory block monitoring device 5 will be specifically described with reference to FIGS. As shown in FIG. 4, when the memory block is allocated on the memory 9 and the memory block monitoring table 6 has the values shown in FIG. 5, the memory block monitoring device 5 performs the conversion operation shown in FIG. .

FIG. 7 is a flow chart showing the operation of the memory block monitoring device 5. In the memory block monitoring device 5, the memory block monitoring table 6 is used to
Check the given virtual address as shown in. In step 70, if the value of the virtual address received from the CPU 1 is "FF020010", then step 71, step 72, step 73, step 74
In step 75, the real address "0008" is entered.
0010 ”is output to the memory 9. If the value of the virtual address is“ FF020301 ”, the offset is“ 0301 ”and the size is“ 010 ”in step 74.
Since it is 0 ″, the offset becomes larger than the size, so the routine proceeds to step 76, where a conversion error is notified to the CPU 1 through the interrupt line 4.

The value of the virtual address is "00010001"
If so, since the address identifier 30 is "00" in step 71, the process proceeds to step 78, and the real address "00010001" is output to the memory 9. If the value of the virtual address is “FF070000”, the control bit 32 is “1” in step 73.
In step 76, the CPU 1 is notified of the conversion error by the interrupt line 4. The value of the virtual address is "FF
If it is "08010", since the offset is "0010" and the size is "0000" in step 74, the process proceeds to step 76 and the CPU I is notified of the conversion error by the interrupt line 4. If the value is "FF000002", since the block number 31 is "00" in step 72, the process proceeds to step 77, and the address 2 of the memory block monitoring table 6 inside the memory block monitoring device 5 is accessed.

[0010]

As described above, according to the present invention, when a memory block is accessed by a program, it is possible to detect an access outside the range of the memory block. Therefore, an erroneous process of one program is processed by another program. There is an advantage that it can be prevented from making a mistake.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a memory block monitoring table inside the memory block monitoring device shown in FIG.

FIG. 3 is a configuration diagram of virtual addresses passed from a CPU to a memory block monitoring device.

FIG. 4 is an explanatory diagram showing an example of memory block allocation in a memory.

5 is an explanatory diagram showing a configuration example of a memory block monitoring table when a memory block is allocated as shown in FIG.

FIG. 6 is an explanatory diagram showing an example of conversion from a virtual address to a real address.

FIG. 7 is a flowchart showing the operation of the memory block monitoring device.

[Explanation of symbols]

 1 CPU 2,7 Data bus 3,8 Address bus 4 Interrupt line 5 Memory block monitoring device 6 Memory block monitoring table 9 Memory 20 Memory block (N) start real address 21 Memory block (N) size 22 Memory block (N + 1 ) Head real address 23 size of memory block (N + 1) 30 address identifier 31 block number 32 control bit 33 offset 70-78 processing step

Claims (3)

[Claims] 1. A memory block monitoring table for monitoring the states of a plurality of memory blocks forming a memory, a conversion unit for converting a virtual address input from a CPU into a real address on the memory, and the conversion. A monitoring means for monitoring by the memory block monitoring table whether or not the virtual address input from the CPU exceeds the range of the memory block, and a memory provided between the CPU and the memory. A memory block monitoring method configured by a block monitoring device. 2. The memory block monitoring system according to claim 1, wherein the memory block monitoring table is configured to include head real addresses of a plurality of sets of memory blocks and a block size. 3. The memory block monitoring system according to claim 1, wherein the virtual address comprises an address identifier, a control bit, a memory block number, and an offset.