JPH02282832A - Memory protection system for task - Google Patents

Abstract

PURPOSE:To improve the processing efficiency of a memory protection system for tasks by producing the memory protection data only when a task is executed at first, storing this produced data into a load module for tasks and then reading out the protection data to use it when the control is shifted to a current task. CONSTITUTION:A memory protection data saving area 2 is provided in a load module 10 at every task. Then the memory protection data is produced and a set initial routine is carried out only when the control is shifted to a due task at first. The memory protection data is taken out of the area 2 when the control is shifted to a current task. Then the protection data is set to a memory protection register which is controlled by an operation system. Thus it is not required to produce the memory protection data nor to set it to the memory protection register at every execution of a task. Consequently, the overhead can be eliminated for such processes where the memory protection data is produced and set to the memory protection register, and the overall system processing efficiency is improved.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a memory protection scheme for tasks.

(Prior Art) Computers generally have an operating system (O8
) or execute various tasks under the control of the monitor, among which the single-tasking function is used to control only a single task, and the multi-tasking function is used to execute multiple tasks alternately. That's what I say.

By the way, in task management in conventional operating systems with multitasking functions, the time required to switch execution from one task to another is called overhead, and compared to a single task monitor, the time required to switch execution from one task to another is called overhead. Generally, the shorter this time, the better the performance.

In a conventional small-scale operating system with a multitasking function, each time before transferring control to a task, the task checks its own writable area, and stores this data as memory protection data. A task is executed while managing the range of memory protection data set in the memory protection register so that it can be used as various working areas etc. that can be used to execute the task.

Therefore, when transferring control to another task, a series of processes such as checking the writable area, generating memory protection data, and setting the memory protection register are necessary.
The overhead was large and the overall system processing efficiency was reduced.

Key θth (Problem that 0JIF# tries to solve) As mentioned above, in task management of a small operating system with multitasking function, a task can write by itself each time before transferring control to another task. Investigate the area,
It was set in the memory protection register as memory protection data. Therefore, when transferring control to another task, a series of processes such as checking the writable area, generating memory protection data, and setting the memory protection register are performed, resulting in a large overhead. There was a problem in that the processing efficiency of the overall system was reduced.

Therefore, the purpose of this invention is to generate memory protection data for each task only when control is transferred to that task for the first time, so that it is not necessary to generate it each time a task is executed, so that the generation process The object of the present invention is to provide a task memory protection control method that removes the processing overhead and thereby improves the processing efficiency of the overall system.

[Configuration of the Invention (Means for Solving the Problem) In order to achieve the above object, the present invention is configured as follows. In other words, in an operating system that has a multitasking function that executes multiple tasks alternately, a memory-protected data save area is provided in the load module for each task, and each task can be written to by itself when control is transferred for the first time. The available memory area information is generated based on the available memory area information, and the information is set in the memory protection data save area and in the memory protection register managed by the operating system. The memory area used by the execution task is managed using register setting information, and from then on, when transferring control to the current task, the memory protection data is retrieved from the memory protection data save area, set in the memory protection register, and used for management. I'll do what I do.

(Function) In the present invention, when control is first transferred to a task in the memory protection data save area provided in the load module for each task, the memory area that can be written by the task itself is checked and memory protection data is generated. and save it and set it in the memory protection register. Thereafter, when transferring control to the current task, the memory protection data is retrieved from the memory protection data save area and set in the memory protection register. This eliminates the processing overhead of generating memory protection data every time control is transferred to another task.

In this way, a memory protection data save area is provided in the load module for each task, and the initial routine for generating and setting memory protection data is executed only when control is transferred to the task for the first time. When transferring control to the memory protection data save area, the memory protection data is retrieved from the memory protection data save area and set in the memory protection register managed by the operating system.Memory protection data is generated every time a task is executed, and the memory protection data is set in the memory protection register. Since this process is no longer necessary, the overhead of transferring control to other tasks can be removed, and the overall system processing efficiency can be improved. .

(Example) Next, an example of the present invention will be described with reference to the drawings. FIG. 1 shows the format of a task load module IO to which the present invention is applied. As shown in the figure, the load module of each task consists of at least a branch instruction area 1 to the first block of the program, a memory protection data save area 2, and a program logic section 3. Each task has a routine that is executed only when it executes for the first time: a routine that checks the writable memory area by itself, a routine that generates memory protection data from the results of this check, and a routine that generates memory A routine is provided to set the protected data in the memory protected data save area 2 and set the memory protected data in the memory protected register managed by the operating system, and this series of routines is set to be executed only at the initial stage. In addition, when the operation system that manages the execution of a task transfers control to a certain task, it does not execute the above initial execution routine unless the task is to be executed for the first time, and stores the memory protection data save area 2 of the task. After reading the memory protection data stored in the memory protection register and setting it in the memory protection register managed by the operating system, the program branches to the logic section 3 to execute the task.

In this method, the operating system executes each task sequentially and alternately, but the initial routine is executed only for the first execution of each task, and is set in the memory protected data save area 2 of that task from the next execution. After reading out the memory protection data and setting it in the memory protection register managed by the operating system, the program logic section 3 of the task is branched to execute the task. That is, the operating system executes the initial routine of each task only at the first execution, checks the writable memory area by the task itself, generates memory protection data, and transfers it to the load module IO for each task. The data is set in the memory protection data save area 1 provided in the memory protection data save area 1, and is also set in the memory protection register of the operating system.

Then, the task is executed while referring to the memory protection data in the memory protection register and using the address range indicated by this data as a working area. Then, after transferring control to another task, the next time it is executed, the memory protection data set in the memory protection data save area 2 of that task is read out and set in the memory protection register managed by the operating system. , it switches to the initial routine and moves on to executing that task.

In this way, memory protection data save area 1 is provided in the load module IO for each task, and only when control is transferred to the task for the first time, the initial routine for generating and setting memory protection data is executed, and then the current When transferring control to a task, the memory protection data is extracted from the memory protection data save area 1 and set in the memory protection register managed by the operating system, so that the memory protection data is generated every time the task is executed. This eliminates the need for settings such as settings. This makes it possible to eliminate the processing overhead of generating memory protection data and setting it in the memory protection register, thereby improving the processing efficiency of the overall system.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof.

[Effects of the Invention] As explained above, according to this method, in multitasking, memory protection data is generated only when a task is executed for the first time, and this data is saved in the load module of the task. However, by reading and using the saved memory protection data when transferring control to the current task, it is no longer necessary to generate memory protection data each time, and the processing overhead of generating memory protection data is reduced. By removing this, it is possible to provide a task memory protection scheme that can increase the overall system processing efficiency.

[Brief explanation of drawings]

FIG. 1 is a memory map showing one embodiment of the present invention. 1... Program branch instruction area, 2... Memory protection data save area, 3... Program logic section, 10... Task load module.

Claims (1)

[Claims] In an operating system having a multitasking function that alternately executes multiple tasks, a memory-protected data save area is provided in the load module for each task, and each task has a Checks the memory area that can be written by itself, generates usable memory area information based on the information, sets it in the memory protection data save area, and also sets it in the memory protection register managed by the operating system. uses the setting information of this memory protection register to manage the memory area used by the execution task, and from then on, when transferring control to the current task, the memory protection data is retrieved from the memory protection data save area and set in the memory protection register. A task memory protection method characterized by being used for task management.