Patent Publication Number: US-7594094-B2

Title: Move data facility with optional specifications

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application contains subject matter which is related to the subject matter of the following application, which is assigned to the same assignee as this application. The below listed application is hereby incorporated herein by reference in its entirety: 
   “FACILITATING USE OF STORAGE ACCESS KEYS TO ACCESS STORAGE,” Dan F. Greiner, Ser. No. 11/437,218, filed herewith. 
   TECHNICAL FIELD 
   This invention relates, in general, to processing within a processing environment, and in particular, to moving data between address spaces of the processing environment. 
   BACKGROUND OF THE INVENTION 
   Address spaces are used to provide degrees of isolation between users. In one example, such as in the z/Architecture offered by International Business Machines Corporation, an address space is a consecutive sequence of integer numbers (i.e., virtual addresses) together with the specific transformation parameters that allow each number to be associated with a byte location in storage. The virtual addresses designate locations in virtual storage. Virtual storage gives the appearance of a larger main storage to the users of the environment. 
   When a virtual address is used by a central processing unit (CPU) to access main storage, it is first converted to a real address by, for instance, dynamic address translation (DAT), and then, to an absolute address by, for instance, prefixing. DAT may use from five to two levels of tables (e.g., region first table, region second table, region third table, segment table, and page table) as transformation parameters. The designation (origin and length) of the highest level table for a specific address space is called an address space control element, and it is found in a control register or is specified by an access register. Alternatively, the address space control element for an address space may be a real space designation, which indicates that DAT is to translate the virtual address simply by treating it as a real address and without using any tables. 
   DAT uses, at different times, the address space control elements in different control registers or specified by the access registers. The choice is determined by the translation mode specified in the current program status word (PSW). Four translation modes are available: primary space mode, secondary space mode, access register mode, and home space mode. Different address spaces are addressable depending on the translation mode. 
   DAT, prefixing, and other features associated with virtual storage and address spaces are described in  z/Architecture: Principles of Operation , IBM® Publication No. SA22-7832-04, September 2005, which is hereby incorporated herein by reference in its entirety. 
   There are situations in which data is to be moved from one address space to another address space. Currently, in the z/Architecture, there is an instruction to move data from the primary address space to the secondary address space (MVCP), and another instruction to move data from the secondary address space to the primary address space (MVCS). For each type of move, a separate instruction is necessary, and the source and target address spaces are predefined by the individual instructions. Each instruction is used to move a maximum of 256 characters per execution from the source address space of the instruction to the target address space of the instruction. To move more than 256 characters, multiple instruction executions are required. 
   In addition to the above, data can be moved from one address space to another address space in the z/Architecture by using access registers. However, in order to perform the move using access registers, the structure for such a move, including operating system modifications, must be in place. 
   SUMMARY OF THE INVENTION 
   Based on the foregoing, a need exists for a move data facility that does not require operating system modifications and allows data to be moved from any address space to any other address space. 
   Further, a need exists for a move data facility that does not require a separate instruction for each type of move and does not require the predefining of the source and target address spaces in the individual instructions. For instance, a need exists for a facility that enables data to be moved from any address space to any other address space using a single instruction. Yet further, a need exists for an instruction that can also support other optional specifications. For instance, a need exists for an instruction and/or facility that enables the flexible selection of storage access keys for the access of storage. Moreover, a need exists for the capability of further performance enhancements, such as the ability to move more than 256 characters of data per instruction execution. 
   The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a method of moving data in a processing environment. The method includes, for instance, providing an instruction to move data from a source address space to a target address space; specifying for the instruction a source address space mode used to determine the source address space from which data is to be moved and a target address space mode used to determine the target address space to which the data is to be moved, wherein the source address space mode and the target address space mode are not statically predefined by the instruction; and using the instruction to move data from the source address space to the target address space. 
   In another aspect, a method of moving data in a processing environment is provided, in which the method includes, for instance, selecting a source address space mode used to determine a source address space from which data is to be moved and a target address space mode used to determine a target address space to which data is to be moved, the source address space mode and the target address space mode being selected from any of a plurality of address space modes, the plurality of address space modes comprising at least one address space mode other than a primary address space mode and a secondary address space mode; and moving data from the source address space to the target address space, wherein the selecting and moving are provided absent operating system modifications to support the selecting and the moving. 
   In still a further aspect of the present invention, an instruction is provided. The instruction includes, for instance, an operation code to identify a move data instruction to be executed; a first set of one or more fields to identify a first operand; a second set of one or more fields to identify a second operand; a third field to identify a length of data to be moved from the second operand to the first operand; and an input control to control access to the first operand and the second operand, the input control including, for instance, a first set of controls including an optional first address space mode used to determine a first address space for the first operand, a first address space control indicating whether the first address space mode in the input control or in a system register is to be selected, an optional first access key to control access to the first operand, and a first access key control indicating whether the first access key in the input control or in the system register is to be selected; and a second set of controls including an optional second address space mode used to determine a second address space for the second operand, a second address space control indicating whether the second address space mode in the input control or in the system register is to be selected, an optional second access key to control access to the second operand, and a second access key control indicating whether the second access key in the input control or in the system register is to be selected. 
   System and computer program products corresponding to one or more of the above-summarized methods are also described and claimed herein. 
   Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One or more aspects of the present invention are particularly pointed out and distinctly claimed as examples in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
       FIG. 1  depicts one embodiment of a processing environment incorporating and using one or more aspects of the present invention; 
       FIG. 2  depicts one embodiment of the logic associated with an overview of a move data facility, in accordance with an aspect of the present invention; 
       FIG. 3  depicts one example of a format of a Move with Optional Specifications instruction provided in accordance with an aspect of the present invention; 
       FIG. 4   a  depicts one embodiment of the fields of general register  0  used by the Move with Optional Specifications instruction of one aspect of the present invention; 
       FIG. 4   b  depicts one embodiment of the fields associated with an operand access control of general register  0 , in accordance with an aspect of the present invention; 
       FIG. 5  depicts one embodiment of the logic associated with executing the Move with Optional Specifications instruction, in accordance with an aspect of the present invention; 
       FIG. 6  depicts one embodiment of employing an operand access control to determine the specified address space and access key to be used in the move operation, in accordance with an aspect of the present invention; 
       FIG. 7  depicts one embodiment of the logic associated with address resolution, in accordance with an aspect of the present invention; 
       FIG. 8  depicts one embodiment of moving data from a source operand to a target operand, in accordance with an aspect of the present invention; and 
       FIG. 9  depicts one example of a computer program product incorporating one or more aspects of the present invention. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   In accordance with an aspect of the present invention, a move data facility is provided that enables optional specifications to be indicated to flexibly control the move operation. Data may be moved from any address space to any other address space without modifying the operating system to support such a move, and in one example, by using a single instruction. Further, any storage access keys can be selected to access the storage used in the move. A maximum of, for instance, 4096 characters can be moved in one execution of the instruction. 
   One embodiment of a processing environment incorporating and using one or more aspects of the present invention is described with reference to  FIG. 1 . Processing environment  100  is, for instance, a multi-processing environment including a plurality of processors  102  (e.g., central processing units (CPUs)), a memory  104  (e.g., main memory) and one or more input/output (I/O) devices  106  coupled to one another via, for example, one or more buses  108  or other connections. 
   As one example, each processor  102  is an IBM System Z™ server, offered by International Business Machines Corporation, Armonk, N.Y., and one or more of the processors execute an operating system, such as z/OS®, also offered by International Business Machines Corporation. (z/OS and IBM are registered trademarks of International Business Machines Corporation, Armonk, N.Y., USA. Other names used herein may be registered trademarks, trademarks or product names of International Business Machines Corporation or other companies.) 
   Processing within the processing environment is facilitated by the provision of a move data facility that enables flexible control of a move data operation. With reference to  FIG. 2 , a general overview of the facility is provided. Data is moved from any address space to any other address space, and in one example, the storage for the move is accessed using any selected storage access keys, STEP  200 . The data move is performed, in one embodiment, without requiring modification to the operating system including, for instance, modification to support access register mode. Further, in one embodiment, a single instruction is used that does not require static definition of the address spaces and/or storage access keys. The instruction includes optional specifications that enable the selection of the desired addresses from which/to data is to be moved, and the selection of the storage access keys for accessing the source operand and the target operand of the instruction. 
   In the embodiment in which an instruction is used to move the data, the instruction can be implemented in many architectures and may be emulated. As examples, the instruction is executed in hardware by a processor; or by emulation of an instruction set that includes this instruction, by software executing on a processing unit having a different native instruction set. In one particular example, the instruction is implemented in the z/Architecture, offered by International Business Machines Corporation, and is referred to herein as a Move with Optional Specifications (MVCOS) instruction. 
   A Move with Optional Specifications instruction  300  ( FIG. 3 ) includes, for instance, an operation code  302   a ,  302   b  designating the Move with Optional Specifications instruction; a general register  304 , the contents of which specify a third operand used by the instruction, and includes, for instance, an unsigned binary integer called the true length, which is the true length of the data to be moved; a base register  306 , which may be any of sixteen general purpose registers of the processing unit and includes a portion of an address of a first operand in storage used by the instruction; a displacement value  308 , which is, for instance, an unsigned 12 bit binary number added to the contents of register  306  to provide the address of the first operand in storage; a base register  310 , which again is any of the sixteen general purpose registers in the processing unit and includes a portion of an address of a second operand in storage used by the instruction; and a displacement value  312 , which is added to the contents of register  310  to provide the address of the second operand in storage for the instruction. The addresses of the first and second operands are virtual addresses, in one embodiment. 
   In addition to the registers described above, the Move with Optional Specifications instruction also implicitly uses a general register, general register  0 , that does not have to be encoded in the instruction, but is used by the instruction. This register is referred to herein as a user register, since it is intended to be updated by users of the move instruction. 
   General register  0  ( 400 ,  FIG. 4   a ) includes, for instance, an operand access control (OAC)  1  ( 402 ) that is used to control access of the first operand, and operand access control  2  ( 404 ) that is used to control access of the second operand. One example of the fields associated with each of operand access controls  402 ,  404  is described with reference to  FIG. 4   b . In one example, each operand access control includes the following fields:
         Specified Access Key (Key)  412 : The specified access key is used to access the operand (e.g., first operand, if OAC  402 ; and second operand if OAC  404 ), if the specified access key validity control (K) is one, as an example; otherwise, the specified access key is ignored.   Specified Address Space Control (AS)  414 : The specified address space control is used to access the operand when the address space control validity control (A) is one; otherwise, the specified address space control is ignored. As examples, the specified address space control includes: 00 for primary space mode; 01 for access register mode; 10 for secondary space mode; and 11 for home space mode.   Specified Access Key Validity Control (K)  416 : This value controls whether a key in a system register, such as the program status word (PSW), or the specified access key is to be used to access the operand. When the control is 0, for instance, the PSW key is used. However, when the control is 1, for instance, the specified access key is used. As used herein, a system register is a register in which the user of the move instruction is not expected and/or allowed to directly revise.   Specified Address Space Control Validity Control (A)  418 : This controls whether the address space control in the current PSW or the address space control in the specified address space control is to be used to access the operand. When the A control is 0, for instance, the address space control in the current PSW is used. When the A control is 1, for instance, the specified address space control is used.       

   Although examples of registers are described above, each of the registers may include more, less or different information. Further, each may include additional data not necessarily needed in one or more aspects of the present invention. The specific location within the registers for the information is implementation and/or architecture dependent. 
   One embodiment of the logic associated with the Move with Optional Specifications instruction is described with reference to  FIG. 5 . As one example, this instruction is executed by one or more processors of the processing environment. 
   In response to executing the instruction, a determination is made as to the storage keys to be used for the source and target operands, STEP  500 . As used herein, the source operand is the second operand of the instruction and the target operand is the first operand. Each of the source operand and the target operand is to have its own storage access key associated therewith. The storage access key for a particular operand is specified in the operand access control for that operand (e.g., OAC  1  for the target operand or OAC  2  for the source operand) or in the program status word. 
   To determine whether the storage access key in the operand access control or the program status word is to be used for a particular operand, a selection protocol is employed. For instance, as depicted in  FIG. 6 , a multiplexor  600  is used to select the storage access key. Input to multiplexor  600  is a key  602  of a program status word  604 , as well as a key  606  of an operand access control  608 . The operand access control employed depends on whether it is the target or source operand for which the determination is being made (e.g., OAC  1  for the target operand or OAC  2  for the source operand). Further input to multiplexor  600  is specified access key validity control  610 . If this control is 0, then, in one example, key  602  is used. However, if this control has a value of 1, then key  606  is used. This provides flexibility in the selection of the access key to be used for both the source operand and the target operand. 
   Returning to  FIG. 5 , in addition to determining the storage keys to be used, a determination is made as to the address spaces of the source and target operands to be used, STEP  502 . As with the storage keys, the selection of the address spaces is also controlled by specifying the desired address space control modes and using a selection control. For instance, as depicted in  FIG. 6 , a multiplexor  620  is used to select the effective address space. Input to multiplexor  620  is a specified address space control  622  of operand access control  608  (e.g., OAC  1  for the target operand or OAC  2  for the source operand), and an address space control  624  of PSW  604 . Further input to multiplexor  620  is a specified address space control validity control  626 , which controls whether the address space control of the PSW or the operand access control is to be used to access the operand. When the specified address space control validity control is, for instance, 0, then the address space control  624  in the current PSW is used. However, when the specified address space control validity control is, for instance, 1, then specified address space control  622  is used. The address space control is, for instance, a 2 bit field, which indicates the selected address space mode. 
   After determining the address spaces from which the source and target operands are to be accessed, the addresses of the source and target operands are determined, STEP  504 . In particular, since in this embodiment, the operands are virtual addresses, the virtual addresses are translated to absolute addresses. 
   One embodiment of the logic associated with resolving the operands is described with reference to  FIG. 7 . An address  700  of an operand to be resolved is specified in the form of a base register  702  and a displacement  704 . This is the virtual address  706  of the operand, which is input to dynamic address translation  708 . Also input to dynamic address translation is an effective address space control element  710 , which is determined from a selection control, such as a multiplexor  712 . Input to the multiplexor is the effective address space obtained, for instance, from  FIG. 6 , as well as various control registers and an access register translation, when applicable. The output of multiplexor  712  is the effective address space control element (ASCE) that is input to dynamic address translation. For instance, if effective AS  714  is 00, then CR 1  is selected, which indicates primary address space mode. Likewise, if effective AS  714  is 01, then access register mode is selected, etc. The address space control element designates one or more particular tables, depending on the input to multiplexor  712 , that are used by DAT to translate the virtual address to a real address. The output of the dynamic address translation is a real address of the operand, which is subject to prefixing  722  providing an absolute address  724  of the operand. Prefixing is a mechanism by which rules are applied to determine the absolute address of a real address. Further details associated with dynamic address translation and prefixing, as well as other virtual addressing concepts, are described in  z/Architecture: Principles of Operation , IBM® Publication No. SA22-7832-04, September 2005, which is hereby incorporated herein by reference in its entirety. 
   Subsequent to determining the addresses of the source and target operands, the data is moved from the source operand to the target operand, STEP  506 . The amount of data moved is specified by the third operand of the instruction. This is pictorially depicted in  FIG. 8 . As shown, data of a second operand  800 , as designated by B 2 D 2    804  is moved to a first operand  806 , as designated by B 1 D 1    808 . The number of bytes moved is specified  810  by a third operand  812 . In accordance with an aspect of the present invention, up to, for instance 4,096 characters can be moved in one execution of the instruction. For instance, the designated amount of characters are copied from the source to the target. Multiple executions of the instruction can be used to move additional bytes of data. 
   Described in detail above is a flexible move data facility that enables the moving of data from any address space to any other address space using any specified access control keys. Further, the amount of data to be moved is specifiable. 
   An example of moving 16 K bytes of data from the secondary address space to the home address space is depicted below. In this example, the first operand is accessed using the PSW key and the second operand is accessed using Key  5 .
         LA 3,OPERAND1   LA 5,OPERAND2   LHI 7,16384   LLILF 0,X′00C15083′   LOOP MVCOS 0(3),0(5),7   AHI 3,4096   AHI 5,4096   AHI 7,-4096   BP LOOP       

   In the above example ‘00C1’ are the contents of OAC 1  and ‘5083’ are the contents of OAC 2 . Further, of the OAC, in one example, bits  0 - 3  (left to right) are the specified key, bits  8 - 9  are the specified address space control, bit  14  is the specified key validity bit and bit  15  is the specified ASC validity bit. 
   One or more aspects of the present invention can be included in an article of manufacture (e.g., one or more computer program products) having, for instance, computer usable media. The media has therein, for instance, computer readable program code means or logic (e.g., instructions, code, commands, etc.) to provide and facilitate the capabilities of the present invention. The article of manufacture can be included as a part of a computer system or sold separately. 
   One example of an article of manufacture or a computer program product incorporating one or more aspects of the present invention is described with reference to  FIG. 9 . A computer program product  900  includes, for instance, one or more computer usable media  902  to store computer readable program code means or logic  904  thereon to provide and facilitate one or more aspects of the present invention. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Examples of a computer readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. 
   A sequence of program instructions or a logical assembly of one or more interrelated modules defined by one or more computer readable program code means or logic direct the performance of one or more aspects of the present invention. 
   Advantageously, one or more aspects of the present invention provide a move data facility that can support optional specifications for the move. A facility is provided in which data can be moved from any address space mode (e.g., primary, secondary, access register specified, home or PSW specified) to any other address mode without requiring operating system enhancements, such as, for instance, the provision of access register mode. The address space mode for either operand can be explicitly designated or provided by default in the current program status word. In one embodiment, an instruction is used to move the data from any address space to any other address space. The instruction does not require the static definition of address space modes. Further, the facility provides for moving more data in one execution of the instruction than typically allowed. No new hardware registers or tables are used to provide this functionality. Additionally, the storage protection key for either or both storage operands can be specified by the program or default values may be used from the program status word. 
   Although one or more examples have been provided herein, these are only examples. Many variations are possible without departing from the spirit of the present invention. For instance, processing environments other than the example provided herein may include and/or benefit from one or more aspects of the present invention. As an example, one or more processors can be other than IBM System Z™ processors and/or execute operating systems other than z/OS®. Further, the environment need not be based on the z/Architecture, but instead, can be based on other architectures, offered by, for instance, Intel, Sun Microsystems, as well as others. Yet further, the instruction can include other registers or entities other than registers to designate information. Further, different data and/or positioning within the registers and/or entities are possible. Still further, although a maximum of 4096 characters is provided as an example of the number of characters that can be moved in one execution of the move instruction, any other number of characters is possible, including an unlimited number and allowing the instruction to be interruptible. Many other variations exist. 
   As further examples, system registers other than the PSW can include default values for the address space mode and/or access keys. Also, other registers can be used for one or more of the OACs. Yet further, although values for controls are provided, other values may be used without departing from the spirit of the present invention. Moreover, the use of DAT and/or prefixing to translate from a virtual address to an absolute address is only one example. The translation can be performed in a number of ways, including, but not limited to, table lookups. 
   Moreover, an environment may include an emulator (e.g., software or other emulation mechanisms), in which a particular architecture or subset thereof is emulated. In such an environment, one or more emulation functions of the emulator can implement one or more aspects of the present invention, even though a computer executing the emulator may have a different architecture than the capabilities being emulated. As one example, in emulation mode, the specific instruction or operation being emulated is decoded, and an appropriate emulation function is built to implement the individual instruction or operation. 
   In an emulation environment, a host computer includes, for instance, a memory to store instructions and data; an instruction fetch unit to fetch instructions from memory and to optionally, provide local buffering for the fetched instruction; an instruction decode unit to receive the instruction fetch unit and to determine the type of instructions that have been fetched; and an instruction execution unit to execute the instructions. Execution may include loading data into a register for memory; storing data back to memory from a register; or performing some type of arithmetic or logical operation, as determined by the decode unit. In one example, each unit is implemented in software. For instance, the operations being performed by the units are implemented as one or more subroutines within emulator software. 
   Further, a data processing system suitable for storing and/or executing program code is usable that includes at least one processor coupled directly or indirectly to memory elements through a system bus. The memory elements include, for instance, local memory employed during actual execution of the program code, bulk storage, and cache memory which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution. 
   Input/Output or I/O devices (including, but not limited to, keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers. Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modems and Ethernet cards are just a few of the available types of network adapters. 
   As used herein, the term “operand” not only includes and/or refers to operands of an instruction, but also other operands, as well as parameters or arguments passed between functions of programs, or any other data that is passed between entities. 
   The capabilities of one or more aspects of the present invention can be implemented in software, firmware, hardware or some combination thereof. At least one program storage device readable by a machine embodying at least one program of instructions executable by the machine to perform the capabilities of the present invention can be provided. 
   The flow diagrams depicted herein are just examples. There may be many variations to these diagrams or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention. 
   Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.