JPH10289158A - Task management device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve system reliability in a real time system of an intervention control system. SOLUTION: For the loading request of an object file 140 from an application program, a real time OS reads the management block 130 of a nonvolatile memory 120, retrieves the file 140, activates a module, allocates an area for storing the text segment 310 and data segment 320 of the file 140 to a volatile memory 150, stores the segment 310 and segment 320 of the file 140 to the segment 345 and segment 350 of the memory 150, reads the symbol information 325 of a large area variable to which an address is not allocated, allocates the address, activates a memory management module and sets the protective bit of the page table entry of the page table 170 of an MMU 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a task management device.

[0002]

2. Description of the Related Art In a real-time OS used in a built-in control microcomputer system, applications are collectively linked, so that a text segment 500 and a data segment 510 can be accessed from all tasks as shown in FIG. Stack segment 5
20 to 550 are retained for each task (Interface December 1993, pages 78 to 79).

[0003]

At this time, since all global variables are stored in the data segment 510, another task erroneously rewrites a global variable used only by a certain task. Problem.

An object of the present invention is to provide an optimum task management method for protecting a task in a real-time OS of an embedded control microcomputer system. That is, an address space of a text segment and a data segment is assigned to each task, and the above text and data segments are protected from access by other tasks by using a protection mechanism of a memory management mechanism, so that a certain task runs away. An object of the present invention is to provide a highly reliable system for protecting a task by preventing the rewriting of the text segment and the data segment at times.

[0005]

In order to achieve the above object, according to the present invention, an object management block for storing information of an application program stored in a non-volatile memory, and an object management block for storing information of an application program by the object management block. An object management module that returns the address of the application program in the non-volatile memory at the time of a program execution request, and stores the application program in the volatile memory from the non-volatile memory, and for a global variable that is not assigned an address. A dynamic link module for allocating addresses and a memory management module for rewriting protection bits of pages corresponding to text segments and data segments when performing task switching are provided.

The real-time OS activates an object management module in response to a loading request of an object file stored in the nonvolatile memory from the application program, and searches the object management block in the nonvolatile memory to execute the application program. Searches for and returns the address that stores the executable file.

The dynamic link module reads the object file header from the storage address of the nonvolatile memory returned from the object management module,
The size and storage address of the text segment and the data segment are calculated, and the area of each segment is allocated from the heap area. Use the object file's symbol table to assign addresses to unlinked global variables.

When the task switching occurs, the memory management program prohibits access to the page table corresponding to the text segment and the data segment, and sets the text segment and the data segment of the task to be executed to be accessible.

[0009]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embedded control microcomputer system according to an embodiment of the present invention.

The embedded control microcomputer system includes a CPU 100, an MMU 110, a nonvolatile memory 120, and a volatile memory 150.

The non-volatile memory 120 stores an object management block 130 and a plurality of object files 140.

The volatile memory 150 stores an object file 160 and a page table 170.

The real-time OS includes an object management module 200, a dynamic link loader module 1
80 and the memory management module 190 are activated to implement protection of the object file 160.

FIG. 2 shows the contents of the block shown in FIG. 1 in detail.

The object management block 130 comprises an object file name 230 and a storage address 240 of the object file.

The object file 140 includes an object file header 260, a text segment 310, a data segment 320, and symbol information 325.

The object file header 260 indicates a text size 270 of the text segment 310, a data size 280 of the data segment 320, a text address 290 indicating an offset value of the text segment 310 from the head of the object file, and an offset value of the data segment 320. It consists of a data address 300.

In the volatile memory 150, the page table 170, the text segment 345, the data segment 350, the stack segment 360, and the T
A CB (Task Control Block) 370 and system symbol information 380 are set.

Next, the operation of one embodiment of the present invention will be described.

When the real-time OS receives a loading request for the object file 140 from the application program, the real-time OS reads the object management block 130 from a fixed address in the nonvolatile memory 120.
The object management block 130 is a non-volatile memory 12
0, the real-time OS compares the object file name 230 with the object file name requested by the application program by activating the object management module 200. If so, the storage address 240 of the object file 140
Returns the value of. If not, return an error value,
The real-time OS notifies the application program that the object file does not exist.

The real-time OS sends a text segment 310 and a data segment 310 of the object file 140 to the dynamic link loader module 180.
Develop 320 onto volatile memory 150 and request that addresses be assigned to unlinked global variables.

Dynamic link load module 18
If the value is 0, the value of the storage address 240 is returned from the object management module 200, and the object file header 260 of the object file 140 is read from the address of the storage address 240. Text size 270 and data size 28 of object file header 260
From 0, the memory management module 190 is requested to allocate an area having a text size 270 and a data size 280 from the heap area from an address in which the page size of the MMU 110 is aligned. If the memory management module 190 successfully allocates the memory, the dynamic link loader module 180 copies the data of the text segment 310 and the data segment 320 of the nonvolatile memory 120 to the text segment 345 and the data segment 350 of the volatile memory 150. I do.

Next, the dynamic link module 180
Reads the symbol information 325 of the object file 140, calculates the address of the global variable from the address assigned by the memory management module 190 for the global variable to which the address has not yet been assigned, and stores the address of the global variable in the specified address of the text segment 345. Set the address of a global variable. When a global variable on the real-time OS is used, the address of the global variable is obtained from the system symbol information 380, and the address of the global variable is set to the specified address of the text segment 345.

If the memory management module 190 cannot allocate a sufficient area, or if there is a global variable whose address is undefined, the dynamic link loader 18
0 reports an error to the real-time OS.

After the real-time OS completes the processing of the dynamic link loader 180, the memory management module 19
For 0, it requests the creation of the page table 170 and the setting of the protection bit.

The memory management module 190 calculates the size of the page table 170 from a value obtained by dividing the text size 280 and the data size 290 of the text segment 345 and the data segment 350 allocated by the dynamic link loader 180 by the page size of the MMU 110, An area on the volatile memory 150 is allocated.

The memory management module 190 stores the allocated address of the page table 170, the text segment 345, and the start index of the data segment 350 in the TCB 370.

A value is set in the protection bit of the page table entry of the page table 170 corresponding to the text segment 345 and the data segment 350, and the real-time OS is notified that the processing is successful, and the loading of the object file 140 is completed. Notify.

If there is not enough area to allocate the page table 170, the memory management module 1
90 notifies the real-time OS of the error.

When the context switching of the task occurs, the real-time OS can set the value of the page table base register in the MMU 110 to the address of the page table 170 of the newly activated task and access the address space of another task. Lose it.

FIG. 3 shows a processing flowchart.

[0033]

According to the present invention, global variables can be protected by retaining the address space of the text segment and the data segment for each task. For this reason, it is possible to prevent rewriting of global variables from other tasks by using a memory management mechanism in order to share global variables among all tasks as in a conventional real-time OS.

[Brief description of the drawings]

FIG. 1 is a block diagram of a system configuration according to the present invention.

FIG. 2 is a block diagram of a system configuration according to the present invention.

FIG. 3 is a processing flowchart.

FIG. 4 is a conventional memory map diagram.

[Explanation of symbols]

100 CU, 110 MMU, 120 Non-volatile memory, 130 Object management block, 140 Object file, 150 Volatile memory, 160 Object file, 170 Page table, 180
... Dynamic link loader module, 190 ... Memory management module, 200 ... Object management module.

Claims (1)

[Claims] An embedded control microcomputer system comprising a central processing unit, a memory management mechanism, a main memory including a nonvolatile memory and a volatile memory, wherein an object file stored in the nonvolatile memory is provided. An object management block that manages addresses of the object file; an object management module that retrieves the object file from the object management block when loading the object file and obtains a storage address in the nonvolatile memory; Extract the above object file from
A dynamic link module that sets an address to a global variable to which no address is assigned, allocates an area on the volatile memory and stores the object file, and, for the object file, a page table of the memory management mechanism. A task management device, comprising: a memory management module that sets write protection from another task, and protects the object file from data destruction due to unauthorized access from another task.