JPH0764852A - Assurance system for dynamically reserved area - Google Patents

Abstract

PURPOSE:To prevent a software fault due to destruction of an area by preventing one process from reserving the area released by another process just after this release. CONSTITUTION:An area reservation processing part 31 reserves an idle area 14 from an idle area list 15 in accordance with the area reservation request from a dynamic area reservation/release request source 5 to generate a reserved area 11. An area hold processing part 32 initializes the pertinent reserved area 11 in accordance with the area release request from the dynamic area reservation/release request source 5 and chains it as the held area 12 to a held area list 13. When a preliminarily determined release condition is satisfied, an area release processing part 33 checks the wrong access of the held area 12, and the held area 12 is released from the held area list 13 and is chained as the idle area 14 to an idle area list 15 if the wrong access is not executed, but the held area 12 is not released and this state is reported to the dynamic area reservation/release request source 5 if the wrong access is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for guaranteeing a dynamically secured area, and more particularly, it secures an area in response to an area securing request from a dynamic area securing / releasing request source, and releases the area in response to an area releasing request. The present invention relates to a method for guaranteeing a dynamically secured area in a dynamic area secured / released management mechanism that performs

[0002]

2. Description of the Related Art Conventionally, in the dynamic area allocation / release processing of an operating system, an area was dynamically allocated during software execution, and the area was released and reused when it became unnecessary.

By the way, there are cases where another process reserves the same area for another purpose immediately after releasing the area used by a certain process. At this timing, the process used immediately before is the same. There is a case that the software is damaged by illegally accessing the area and destroying the contents, causing malfunction of other processes.

[0004]

In the above-mentioned conventional dynamic area allocation / release processing, immediately after a process during software execution releases an area, another process allocates the area for another purpose. In this case, the process used immediately before may illegally access the same area and destroy the contents, causing the malfunction of other processes, resulting in software failure. Since the execution is progressing, there is a problem that analysis of software failure is difficult and often unknown.

In view of the above points, an object of the present invention is to make a reserved area not a free area immediately but to temporarily hold it as a holding area and then make it a free area, so that another process is immediately released after a process releases the area. It is an object of the present invention to provide a method of guaranteeing a dynamically secured area that prevents the software failure due to the destruction of the area from being prevented by the process of (1) to secure the same area.

In consideration of a plurality of cell pool units, in determining whether or not to return a certain cell pool unit, the number of empty cells existing in other cell pool units is checked, A cell pool dynamic return control system is known in which an undesired control state in which a cell pool unit is acquired immediately after return is prevented (see Japanese Patent Publication No. 3-15210). It is not intended to prevent the software failure due to the destruction of the area by providing the pending state of the area.

[0007]

According to a method of guaranteeing a dynamically secured area of the present invention, an area is secured in accordance with an area securing request from a dynamic area securing / releasing request source, and the area is secured in response to the area releasing request. In the dynamic area allocation / release management mechanism to be released, an area allocation processing unit that allocates an empty area in response to an area allocation request and creates an allocation area, and initializes and holds the corresponding allocation area in response to an area allocation request. Area reservation processing section to be an area,
It has an area release processing unit that inspects an unauthorized access to the reserved area when a predetermined release condition is satisfied and releases the unused area to make a free area if the unauthorized access is not performed.

[0008]

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

FIG. 1 is a block diagram showing the structure of a dynamic reserved area guarantee system according to an embodiment of the present invention. The method of guaranteeing the dynamically secured area according to the present embodiment is based on the dynamically secured / released area 1
And a dynamic area allocation / release management mechanism 2 comprising a dynamic area allocation / release processing section 3 and an area pending state management information section 4,
The main part is composed of the dynamic area reservation / release request source 5.

The dynamic allocation / release area 1 is an area on the main memory (including the virtual address space), and includes the allocation area 11 and
There are a reserved area list 13 in which the reserved area 12 is chained and a free area list 15 in which a free area 14 is chained. Although not specifically shown, the reserved area 12 and the free area 14 are accompanied by a front pointer and a rear pointer for forming the reserved area list 13 and the free area list 15. In addition, size information is attached to the reserved area 11 and the free area 14.

Referring to FIG. 2, the area reservation state management information section 4 manages a head pointer 41, a tail pointer 42, a free area list size 43, a pool reference value 44, and a pool total size 45. There is. Head pointer 41
Indicates the head reserved area 12 of the reserved area list 13, and the tail pointer 42 points at the tail reserved area 12 of the reserved area list 13. The free area list size 43 is the total size of the free areas 14 in the free area list 15. The pool reference value 44 is set to a value of 10% of the total size of the dynamic securement / release area 1 in order to provide a timing for incorporating the reserved area 12 into the free area list 15. The total pool size 45 is the holding area 12 of the holding area list 13.
The total size of is set.

The reserved area list 13 chains the reserved areas 12 in the order in which the area release request is received. The oldest reserved area 12 is pointed to by the head pointer 41, and the newest reserved area 12 is pointed to by the tail pointer 42. To be done. The holding area list 13 is a bidirectional list so that the old holding area 12 or the new holding area 12 can be searched.

The dynamic area reservation / release processing section 3 is provided as a part of the operating system, and has an area reservation processing section 31, an area reservation processing section 32, and an area release processing section 33.
It is configured to include and.

The area reservation processing unit 31 reserves the free area 14 from the free area list 15 of the dynamic reservation / release area 1 in response to the area reservation request from the dynamic area reservation / release request source 5 and reserves it. Region 11 is generated.

In response to an area release request from the dynamic area reservation / release request source 5, the area reservation processor 32 sets the corresponding reservation area 11 of the dynamic reservation / release area 1 as a reservation area 12 and holds area list 13 Chain to.

Referring to FIG. 3, the processing of the area reservation processing section 32 includes an area reservation step 101, an area zero clear step 102, and a normal end notification step 103.

The area releasing processor 33 releases the reserved area 12 from the reserved area list 13 until the pool total size 45 reaches the pool reference value 44 or less when the pool total size 45 reaches the pool reference value 44. , Free space 14
As a chain to the free area list 15. In addition, the area release processing unit 33 makes the free area list 1 when the area reservation request is made.
If the free area 14 does not exist in 5, all the reserved areas 12 in the reserved area list 13 are released, and the free area list 15 is chained as the free area 14.

Referring to FIG. 4, the processing of the area release processing section 33 is performed by an address acquisition step 201, an unauthorized access inspection step 202, and an unauthorized access notification step 20.
3 and the reserved area releasing step 204.

FIG. 5 is a state transition diagram of the area in the guarantee method of the dynamically secured area of this embodiment. The secured area 11 is
Reservation area 12 in response to an area release request that specifies an address
Transition to the reserved area 12, the reserved area 12 transitions to the free area 14 according to the establishment of the release condition, and the free area 14 transitions to the reserved area 11 in response to an area reservation request specifying the size.

Next, the operation of the dynamically secured area guarantee system of this embodiment having the above-mentioned configuration will be described.

When an area reservation request is issued from the dynamic area reservation / release request source 5, the area reservation processor 31 of the dynamic area reservation / release processor 3 requests the size requested from the free area list 15. The minimum free space 14 of the above size
Is secured to form a secured area 11. At the same time, the area reservation processing section 31 subtracts the free area list size 43 of the area reservation state management information section 4. Then, the area reservation processing unit 31 notifies the dynamic area reservation / release request source 5 of the normal end of the area reservation. At this time, if there is no free area 14 larger than the requested size in the free area list 15, the area reservation processing unit 31 causes the area release processing unit 33 to hold the reserved area list 1.
Prompt the release of all the reserved areas 12 of No. 3.

The area release processing section 33 uses the head pointer 41 (or the tail pointer 4 of the area holding state management information section 4).
The address of the first (or last) reserved area 12 of the reserved area list 13 pointed to by 2) is acquired (step 201),
It is checked whether or not illegal data other than zero is written in the reserved area 12 to be released (step 20).
2). When the illegal data is written, the area release processing unit 33 does not release the reserved area 12 because the area cannot be guaranteed, and the dynamic area securement / release request is issued to indicate that the unauthorized access is made. Notify source 5 (step 20)
3). If the illegal data has not been written, it means that there is no illegal access, so the area release processing unit 33 releases the reserved area 12 from the reserved area list 13 and sets the free area list 15 as the free area 14. And the head pointer 41 (or the tail pointer 42), the free area list size 43, and the pool total size 45 of the area pending state management information section 4 are updated (step 204). The area release processing unit 33 repeats this process for all the reserved areas 12 in the reserved area list 13.

On the other hand, when there is an area release request for designating an address from the dynamic area reservation / release request source 5, the area reservation processing section 32 of the dynamic area reservation / release processing section 3 causes the dynamic area reservation / release area 1 to move. Chain the corresponding reserved area 11 as the reserved area 12 to the reserved area list 13 (step 101),
The corresponding holding area 12 is initialized (cleared to zero) (step 102). Along with this, the area reservation processing unit 3
2 updates the tail pointer 42 and the pool total size 45 of the area reservation state management information section 4. Then, the area reservation processing unit 32 notifies the dynamic area reservation / release request source 5 of the normal end of the area release (step 103).

As a result of updating the pool total size 45, when the pool total size 45 reaches the pool reference value 44, the area release processing unit 33 causes the area pending state management information unit 4
The address of the head reserved area 12 of the reserved area list 13 pointed to by the head pointer 41 is acquired (step 201),
It is checked whether or not illegal data other than zero is written in the reserved area 12 to be released (step 20).
2). When the illegal data is written, the area release processing unit 33 does not release the reserved area 12 because the area cannot be guaranteed, and the dynamic area securement / release request is issued to indicate that the unauthorized access is made. Notify source 5 (step 20)
3). If the illegal data has not been written, it means that there is no illegal access, so the area release processing unit 33 releases the reserved area 12 from the reserved area list 13 and sets the free area list 15 as the free area 14. And the head pointer 41, the free area list size 43, and the pool total size 45 of the area pending state management information section 4 are updated (step 204). The area release processing unit 33 repeats this processing until the pool total size 45 becomes equal to or smaller than the pool reference value 44.

[0025]

As described above, according to the present invention, in the dynamic area allocating / releasing process, the reserved area is temporarily set as the reserved area at the time of the area release request, and a certain time elapses before the reserved area is released, and the reserved area is released. Software that is generated by malfunction due to destruction of the reserved area during use by guaranteeing the contents of the free area that is the target of the dynamic area by checking whether there is any unauthorized access when performing The effect is that obstacles can be prevented.

Further, since it is possible to detect unauthorized access, by stopping the operation of the process based on the notification of unauthorized access, it is possible to suppress software runaway and facilitate failure analysis. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a guarantee system of a dynamically secured area according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of contents of an area reservation state management information section in FIG. 1 and a reservation area list.

FIG. 3 is a flowchart showing the processing of an area reservation processing section in FIG.

FIG. 4 is a flowchart showing a process of an area release processing unit in FIG.

FIG. 5 is a state transition diagram of an area in the dynamically secured area guarantee method of the present embodiment.

[Explanation of symbols]

 1 dynamic allocation / release area 2 dynamic area allocation / release management mechanism 3 dynamic area allocation / release processing unit 4 area reserved state management information section 5 dynamic area allocation / release request source 11 reserved area 12 reserved area 13 reserved area List 14 Free area 15 Free area list 31 Area reservation processing section 32 Area reservation processing section 33 Area release processing section 41 Start pointer 42 End pointer 43 Free area list size 44 Pool reference value 45 Pool total size

Claims (4)

[Claims] 1. A dynamic area allocation / release management mechanism that allocates an area in response to an area allocation request from a dynamic area allocation / release request source and releases the area in response to the area release request. Depending on the area release request, an area reservation processing section that reserves a free area and creates a reserved area, an area reservation processing section that initializes the corresponding reserved area to a reserved area, and a predetermined release condition A method for guaranteeing a dynamically secured area, which comprises an area release processing unit that checks for unauthorized access to a reserved area when it is established, and releases it when it is not accessed to make it an empty area. 2. The dynamic allocation according to claim 1, wherein the area release processing unit notifies the holding area without releasing the holding area if an unauthorized access is checked in an unauthorized access inspection of the holding area. Area guarantee method. 3. The area reservation processing section reserves a free area from a free area list to generate a reserved area, and the area reservation processing section initializes the reserved area and chains it as a reserved area in the reserved area list, 2. The dynamically secured area guarantee method according to claim 1, wherein the area release processing unit extracts the reserved area from the reserved area list and chains it as a free area in the free area list. 4. An area reservation state management information section for managing the first pointer, the last pointer, the free list size, the pool reference value and the pool total size of the reservation area list, wherein the release condition is the pool total size of the reservation area. 4. The method for guaranteeing a dynamically secured area according to claim 3, wherein when the pool reference value is reached, and when there is no free area at the time of the area securing request.