Electrical computers and digital processing systems: multicomput – Computer-to-computer session/connection establishing – Network resources access controlling
Reexamination Certificate
2000-09-06
2004-12-14
Follansbee, John (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer-to-computer session/connection establishing
Network resources access controlling
C711S163000, C711S164000, C711S166000, C711S200000
Reexamination Certificate
active
06832257
ABSTRACT:
TECHNICAL FIELD
This invention relate; to a computer having memory protection function, a computer readable recording medium adapted so that address validity collation program is recorded, and an address validity collation method at such a computer, and more particularly to a computer having function in which, in response to request of an object, other object provides memory access, a computer readable recording medium adapted so that address validity collation program executed at such a computer is recorded, and an address validity collation method at such a computer.
BACKGROUND ART
In order to execute program on the computer, it is necessary to protect memory by any means. For example, there are instances where object executed on the computer may intentionally or resultantly issue invalid or inaccurate access request with respect to memory area except for address area permitted with respect to the own object during its execution. Here, it is preferable that object is parallel object referred to in the U.S. patent application Ser. No. 08/678,288 U.S. Pat. No. 6,138,140, in which the invention by the same applicant as this applicant is described. Parallel object is execution unit of process, and is such an object capable of carrying out processing in parallel to other parallel object. In order to maintain stable operation of security or the system, it is necessary to exclude access to invalid address area. In view of the above, in many operating systems, memory protection is realized by utilizing memory management system of processor.
Explanation will now be given in connection with processing of memory protection when access to invalid address area takes place.
FIG. 1
is a block diagram for explaining conventional memory protective operation. Operating system
110
carries out context switch in starting execution of object
101
and sets memory protection information that corresponding object
101
has at memory management system
121
of processor
120
. Further, accesses from the object
101
to memory
102
are carried out all through the memory management system
121
. In this instance, the memory management system
121
carries out check as to whether or not designated address infringes memory protection information set at present in the memory management system
121
. As a result, in the case where there is no infringement, access to actual memory
102
is provided. On the other hand, in the case where there is any infringement, memory access is not carried out, but exception is generated by the memory management system
121
. Information of that exception is notified to the operating system
110
. The operating system
110
analyses exception phenomenon to provide exception processing service corresponding thereto.
In a manner as stated above, access only to a predetermined memory space can be provided from the object
101
. Thus, memory is protected.
Moreover, there are also cases where object
101
carries out memory access through operating system
110
. In such cases, collation relating to validity of address is carried out in the operating system
110
. For example, the operating system
110
provides service for responding to request from object
101
, e.g., system call or API (Application Programing Interface) and there are instances where address is delivered from object
101
at the time of such service request. Ordinarily, this address designates address area permitted for the object
101
and the operating system
110
provides access to such area to carry out service. The operation at this time will be described below.
FIG. 2
is a block diagram for explaining the operation of address collation by the operating system
110
. When the operating system
110
receives service request including address from the object
101
, it investigates or checks validity of address at address collation module
111
before it executes actual service at service processing object
112
. This is necessary processing for the reason described below.
Ordinarily, the operating system
110
has access right with respect to address area of object
101
in addition to address area of the operating system
110
itself for the purpose of realizing service. For this reason, even in the case where address delivered from the object
101
inaccurately designates address area of the operating system
110
, validity cannot be discriminated in memory management system
121
that processor
120
has so that access thereto can be provided. Accordingly, there arises the necessity to discriminate validity of address in advance.
Validity collation of address is ordinarily carried out by sequentially collating, by address collation module
111
, whether or not address delivered infringes memory protection information that object
101
has. Collation result of address is delivered to service processing object
112
. In the case where it is judged that its result is invalid (inaccurate) address, error is sent back to the, object
101
as service result.
However, when there is carried out memory access utilizing function that the operating system
110
provides by the above-described method, it is necessary to carry out validity collation of address at address collation module
111
before address delivered from object
101
is actually used in the operating system
110
, giving rise to the problem that execution processing speed is lowered.
In addition, a method which dose does not collate validity of address is conceivable. In this case, however, since the case where address delivered from the object
101
designates destination of storage of data within the operating system
110
, etc. cannot be checked, there arise the problems that data of the operating system
110
is broken and access is inaccurately provided.
As stated above, the conventional operating systems are required to necessarily carry out validity collation of address before address delivered from object is actually used. For this reason, when validity collation of address is carried out, there was the drawback that the execution speed is lowered in accordance with quantity of memory protective information.
DISCLOSURE OF THE INVENTION
This invention has been made in view of such circumstances, and its object is to provide a computer capable of carrying out, at high speed, with high reliability, memory access that, in accordance with request of an object, other object executes.
Another object of this invention is to provide a computer readable recording medium adapted so that there is recorded exception processing program for permitting the computer to carry out, at high speed, with high reliability, memory access that, in accordance with request of an object, other object executes.
A further object of this invention is to provide an exception processing method for executing, at high speed, with high reliability, memory access that, in accordance with request of an object, other objects executes.
In order to solve the above-described problems, the computer according to this invention is directed to a computer having a function to protect memory by permitting access only to address area designated by memory protection information, the computer comprising: request processing means adapted so that when it receives processing request including memory access to designated address, it executes processing in accordance with the processing request, and when memory access takes place, it outputs access request to address designated by processing request; memory access proxy (agent) means adapted to receive the access request that the request processing means outputs to set memory protection information in which area where object which has outputted processing request can access is caused to be accessible area to output, to processor, memory access instruction corresponding to the access request; and memory management means adapted so that when the memory access instruction that the memory access proxy (agent) means outputs is access except for area set in the memory protection information, it generates exception with respect to the memory acc
Follansbee John
Frommer William S.
Frommer & Lawrence & Haug LLP
Hu Jinsong
Simon Darren M.
LandOfFree
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