JPS619731A - Interruption processing method - Google Patents

Abstract

PURPOSE:To leave the interruption processing peculiar to an interruption produced during the execution of an instruction to a process, by providing a flag area related to the process and an error information area into a main memory. CONSTITUTION:In a process ''1'' is stored to a flag area in case it is desired to perform the processing of an interruption produced during execution of an instruction by the process itself. While ''0'' is stored previously to an error area and an instruction is executed for detection of an interruption produced under execution. When no interruption is produced at all, the execution of the next instruction is started as soon as the execution is through with the first instruction. If an interruption is produced during execution of an instruction, an interruption processing program refers to the flag area and completes forcibly the corresponding process in case ''0'' is detected in the flag area. While the value excluding ''0'' which is prescribed to mean the generation of interruption is stored to the error information area when ''1'' is detected in the flag area.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to interrupt processing in computer systems.

Conventional configuration and its problems Interrupts are very frequently used and effective functions in computer systems.
It is used when it is necessary to interrupt the currently executing process and give priority to execution of a more urgent processing program.

Since interrupts are a function shared by all processes executed on a computer system, they are handled uniformly by the operating system.

When an interrupt occurs, the interrupt handling program in the operating system is started, saves the process contypus such as registers and instruction counters used by the interrupted process to a save area such as the interrupt stack, and then executes the next process. After making preparations for restarting the process, execute processing corresponding to the cause of the interrupt. When the interrupt processing is completed, the previously saved registers and the like are restored, and execution of the interrupted process is resumed by executing a return instruction from the interrupt.

Interrupt processing performed by the operating system is
Since it is common to all processes, it is difficult to perform detailed processing according to the differences between each process. Therefore, in the case of an interrupt caused by a fatal failure in a computer system, if there is no general method for dealing with it, the process that caused the interrupt is usually forcibly terminated. For example, an interrupt that occurs when an attempt is made to reference a non-existent main memory corresponds to this. As described above, if the treatment for interrupts is uniform, inconveniences often occur.

In recent years, instructions with advanced functions have often been implemented in computers. These are instructions that are realized in such a way that functions that were conventionally achieved by executing multiple instructions in a series of steps can be executed with a - instruction.For example,
There are instructions that have the function of transferring multiple pieces of data at once from one address to another. This type of instruction may have complicated content to execute, may include a repetitive function, and may take a long time to execute. for example,
When 100,000 pieces of data are transferred using the above transfer command, it takes about 100 milliseconds. This is an extremely long time for computers, which typically execute an instruction in nanoseconds to microseconds.

Interrupts are normally accepted between the end of execution of one instruction and the start of execution of the next instruction. Therefore, as mentioned above, high-performance instructions that occupy the computer for a long time and are executed cannot be interrupted during their execution.
This is inconvenient for interrupt functions. Therefore, many high-performance instructions are implemented so that they can be interrupted even during the execution of the instruction. Of course, even if a side interrupt occurs and instruction execution is interrupted, it is easy to resume instruction execution by saving the current value of the instruction counter. If the value is set to indicate the address where the currently executed instruction is located, no conflicts will occur.

By the way, the operating system tries to deal with interrupts that occur during the execution of high-performance instructions as described above, just as it does with other interrupts.Therefore, fatal failures occur. If you do this, the process will be forcibly terminated, and the results of the execution up to that point will be lost, resulting in a loss. Even if you prevent processes from being forcibly terminated by interrupt handling, this will occur uniformly, causing another inconvenience.In the end, the interrupt handling program However, adding different processing for each process to the interrupt handling program for each process will reduce the versatility of the operating system, and It is usually very difficult to significantly modify the interrupt handling program of an operating system, and it is not a practical method.Therefore, interrupt handling within the operating system can be handled by a uniform procedure, and the process-specific interrupts can be handled by It is best to let the process take its course.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a method that eliminates the drawbacks of the conventional interrupt processing described above, and allows processes to handle process-specific interrupts for interrupts that occur during instruction execution. purpose.

Structure of the Invention The present invention provides a flag area associated with a process and an error information area in the main memory, so that the process and the interrupt processing program can communicate information to each other via the area. By matching, the interrupt processing program is configured to be able to entrust process-specific interrupt processing to a process in response to a request from the process.

The process for explaining the embodiment is as follows: - When an interrupt occurs during instruction execution, if you want to perform the corresponding process yourself, - For example, set the value "1" to the above flag area; otherwise, set the value "0".
is stored in advance, and a value "o" meaning no error information is stored in advance in the error information area, and then execution of the instruction for which an interrupt in the middle of execution is to be detected is started. If no interrupt occurs,
Upon completion of instruction execution, execution of the instruction at the next address begins. On the other hand, if an interrupt occurs during instruction execution that would conventionally cause the process to be forcibly terminated, the interrupt processing program refers to the flag area and changes the value to "o".
If so, the process is forcibly terminated as before, and if the value is "1", a predetermined value other than 0 "', which means the occurrence of an interrupt, is stored in the error information area. As the value to be stored at this time, it is also possible to predetermine a plurality of different values depending on the type of interrupt.

Next, the interrupt handling program adds a certain value determined by the computer to the value of the instruction counter in the saved process context, and the value of the instruction counter indicates the address next to the location address of the interrupted instruction. Change it as follows. Thereafter, when the procedure for returning from the interrupt is executed as usual, execution of the process is resumed from the instruction following the interrupted instruction.

As you can see from the above explanation, by storing the value "1" in the flag area, even if an interrupt occurs during instruction execution, the process will not be forcibly terminated and the next instruction will be executed. It becomes possible to continue to do so. Therefore, after the process finishes executing the instruction for which you want to detect the presence or absence of an interrupt, it checks the error information area, and if the value remains "0", it means that there was no interrupt, so there is no remaining information. It is possible to continue processing, and if it is a value other than "0", it means that there was an interrupt, so it is necessary to judge that there is some kind of abnormality and take corrective action. becomes possible. Therefore, even if some abnormality occurs, it is possible for the process to take measures such as saving the execution results up to that point. Note that the present invention is applicable to a case where the location address of the next instruction after the interrupted instruction can be calculated using a fixed procedure. Further, the present invention does not limit the values stored in the flag area and the error information/area to the values used in the above description.

Effects of the Invention As described above, according to the method of the present invention, only a small amount of certain procedures are added to the interrupt handling of the operating system, which in the past had no choice but to forcefully terminate processes. It enables a process to deal with interrupts that were not present in a way unique to that process, greatly improving the degree of freedom in computer usage, and has a great effect.

Claims (1)

[Claims] If a flag area and an error information area associated with a process are provided in main memory, and the process stores a predetermined value in the flag area, the interrupt handling program that is started when an interrupt occurs , stores the specified error information in the above error information area, changes the value of the instruction counter in the context saved at the time of the interrupt to indicate the location address of the next instruction, and returns from the interrupt. Process execution is resumed from the instruction at the next address, and the process checks the contents of the error information area to determine whether there is an interrupt during the execution of the previous instruction. An interrupt processing method characterized in that, in some cases, it is possible to execute process-specific interrupt processing.