JPH03244054A - Storage protection system - Google Patents

Abstract

PURPOSE:To protect the data area proper to a module by providing a CPU, a storage control part, and a main storage and holding the module IDs in the CPU and the storage control part. CONSTITUTION:When a CPU 2 acquires an instruction, a virtual address is given to a storage control part 3 to ask it to acquire the instruction and the module ID. Then the instruction and the module ID are acquired via the part 3. This module ID is set to a module ID register 21. When the CPU 2 acquires data, a virtual address is given to the part 3 together with the module ID set to the register 21 to ask the part 3 to read and write the data. When the end of the data read/write operations is informed from the part 3, the data read/ write procedure is through. Meanwhile a fault is decided if a read/write unable state is informed from the part 3. Thus it is possible to protect the data proper to a module.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a storage protection method in a computer system that performs virtual storage management.

[Conventional technology]

Conventionally, memory protection has been based on a ring protection method using a virtual memory method and protection levels, and it is not possible to protect data areas specific to modules that constitute an operating system.

[Problem to be solved by the invention]

In the virtual storage system, each process is forced to use an independent storage area for process-specific data areas, so there is no destruction of the process-specific area by other processes. However, data areas commonly used by processes, such as operating system service routines, are not protected.

To compensate for this, there is a ring protection system, in which operating system service routines and the like can only be used at a certain privilege level. Furthermore, within the operating system there are finely controlled privilege levels.

However, even with the above protection schemes, memory protection cannot be achieved between multiple modules related to the same privilege level within the operating system. For example, all input/output drivers are typically set together to the same protection level. In this case, even if the unique area of another output driver is destroyed due to a runaway input/output driver, this abnormality will be detected only when the destroyed input/output driver behaves abnormally, and the cause should be investigated. This is often difficult.

[Means to solve the problem]

The present invention provides a memory protection method for a computer system having a CPU, a memory management section that performs virtual memory management, and a main memory section that stores a text area and a data area, wherein a module ID is retained in the CPU and the storage management section. It is characterized by:

The memory protection method of the present invention is a memory protection method for a computer system having a CPU, a memory management unit that manages virtual memory, and a main memory unit that stores a text area and a data area, and includes a module ID and a physical page address. Text segments consisting of page table entries
It has a storage means including a page table and a data segment page table, a storage management means for extracting a module ID from the text segment page table and a data segment page table, and a module ID holding means for holding the module ID.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a storage protection method according to the present invention.

The components shown in FIG. 1 are a computer system 1, a CPU 2 having a module ID register 21, a storage management section 3, a text segment page table 41, a data segment page table 42, and a text area 43.
The main storage section 4 has a data area 44.

FIG. 2 shows the instruction and data acquisition processing in the CPU 2.

FIG. 3 shows the processing of module (D) in the storage management section 3.

Details of the processing are shown below.

FIG. 2 shows the instruction and data acquisition processing in the CPU 2.

The CPU 2 obtains an instruction or data and controls whether it is an instruction or data (step 201).

When the CPU 2 acquires the instruction, it gives the virtual address to the storage management section 5-3 and requests the acquisition of the instruction and module D (step 211). After that, the command and module ID are obtained from the storage management unit 3 (step 212).
. Further, the module ID obtained from the storage management section is set in the module ID register 21 (step 213).

When the CPU 2 acquires the data, the storage management unit 3
The virtual address and the module ID set in the module ID register 21 are given to request reading and writing of data (step 221).

When notified of the completion of reading and writing from the storage management unit 3 (step 222), reading and writing of data is completed. Further, when receiving a notification from the storage management unit 3 that reading and writing are not possible, a fault occurs (step 223).

FIG. 3 shows the processing of the storage management section 3.

The storage management unit 3 sends commands or data read/write requests to C.
Obtain from PU2 and determine which one was requested (
Step 301).

When the memory management unit 3 is requested by the CPU 2 to read an instruction, it acquires a virtual address from the CPU 2 (step 311), and retrieves the corresponding page table entry from the text segment page table 41 (step 312). . Furthermore, the physical page address and module ID are obtained from the page table entry (step 313). Based on the retrieved physical page address, a virtual address is converted into a physical address, and an instruction is obtained from the main storage unit 4 (step 314).

Thereafter, the instruction and module ID are passed to the CPU 2 (step 315).

When the storage management unit 3 is requested by the CPU 2 to read or write data, it acquires the virtual address and module ID from the CPU 2 (step 321), and retrieves the page table entry corresponding to the virtual address from the data fist segment page table 42. (Step 322). Furthermore, the physical page address and module ID are obtained from the page table e entry (step 323). After that, C
Module ID and data segment obtained from PU2
The module IDs obtained from the page table association entries in the page table 42 are compared (step 324), and if they match, a data read/write operation is performed (step 325).

If they do not match, the CPU is notified that data cannot be read or written (step 326).

As a result of the above, it is prohibited to refer to or change data specific to other modules.

〔Effect of the invention〕

As described in detail above, by applying the storage protection method using the module ID of the present invention, module-specific data can be protected.

This improves the independence of the modules and allows the fault trap φ routine of the operating system to detect module failures and investigate the cause, thereby facilitating maintenance of the operating system.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing instructions and data acquisition processing procedures in the CPU shown in FIG. 1, and FIG. 3 is a diagram showing the storage management shown in FIG. 1. It is a figure showing the processing procedure in the department. 1... Computer system, 2... CPU121...
Module ID register, 3...Storage management unit, 4...
- Main storage unit, 41...Text segment page table, 42...Data segment page table, 43...Text area, 44...Data area.

Claims (1)

[Scope of Claims] 1. In a memory protection method for a computer system having a CPU, a memory management unit that performs virtual memory management, and a main memory unit that stores a text area and a data area, a module ID is provided to the CPU and the storage management unit. A memory protection method characterized by retaining . 2. In a memory protection method for a computer system that has a CPU, a memory management unit that manages virtual memory, and a main memory unit that stores text areas and data areas, a page table entry consisting of a module ID and a physical page address is used. text segment
A storage means including a page table and a data segment page table, a storage management means for extracting a module ID from the text segment page table and a data segment page table, and a module ID holding means for holding the module ID. A memory protection method characterized by: