Patent Publication Number: US-9430399-B2

Title: Multi-core online patching method and apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2011/074094, filed on May 16, 2011, which claims priority to Chinese Patent Application No. 201010505514.4, filed on Oct. 13, 2010, both of which are hereby incorporated by reference in their entireties. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     TECHNICAL FIELD 
     The present invention belongs to the field of computer technologies, and in particular, to a multi-core online patching method and apparatus. 
     BACKGROUND 
     An online patch refers to a patch taking effect in a running program without restarting the program. For a multi-core processor, a current multi-core central processing unit (CPU) with a hardware memory management unit (MMU) supports an online patching function. In an environment of a multi-core CPU, operations such as loading and activation of the online patch are implemented by a master core. 
     As shown in  FIG. 1 , in the patch loading operation of the multi-core CPU, the master core obtains a patch, puts the patch to a cache, parses the patch, extracts code segments and data segments of the patch, and loads the patch according to a logic address. The MMU of the hardware implements the mapping from the logic address to a physical address, and maps core private data to each private data segment in a patch area of a shared memory. 
     In the process of implementing the present invention, the inventors find that, under an MMU condition, because each core in the multi-core CPU accesses the same logic address, and the logic address is mapped to different physical addresses in the patch area, shared global variables of the multi-core CPU cannot be mapped. 
     SUMMARY 
     Embodiments of the present invention provide a multi-core online patching method and apparatus, which can map all patch data to a patch area of a shared memory. 
     Embodiments of the present invention adopt the following technical solutions. 
     A multi-core online patching method includes: separating shared global variables and private global variables in a patch; and mapping the shared global variables to a shared data segment in a patch area by using a mapping mode of a direct memory address, and mapping the private global variables to private data segments in the patch area by using a mapping mode of a variable address specified by a user. 
     A multi-core online patching apparatus includes: a variable separation unit configured to separate shared global variables and private global variables in a patch; and a mapping unit configured to map the shared global variables to a shared data segment in a patch area by using a mapping mode of a direct memory address, and map the private global variables to private data segments in the patch area by using a mapping mode of a variable address specified by a user. 
     It can be known from the above technical solutions of the embodiments of the present invention that, by separating the shared global variables and the private global variables in the patch, mapping the shared global variables to the shared data segment in the patch area by using a mapping mode of a direct memory address, and mapping the private global variables to the private data segments in the patch area by using a mapping mode of a variable address specified by a user, the shared global variables and the private global variables may be mapped at the same time, and mapping all patch data to the patch area of a shared memory is implemented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To make the technical solutions under the present invention clearer, the following describes the accompanying drawings used in the description of the embodiments of the present invention. 
         FIG. 1  is a schematic diagram of an operation process of patch loading of a multi-core CPU in the prior art; 
         FIG. 2  is a schematic diagram of physical address dividing of a patch area according to the present invention; 
         FIG. 3  is a flow chart of an embodiment of a multi-core online patching method provided by the present invention; 
         FIG. 4  is a contrast diagram of a use situation of an external display after a patch is loaded for several times in a patch area and an actual use situation according to the present invention; 
         FIG. 5  is a schematic diagram of a use situation of a patch area before a new patch is loaded according to the present invention; 
         FIG. 6  is a schematic diagram of a use situation of the patch area after a new patch is loaded according to the present invention; 
         FIG. 7  is a schematic diagram of an operation process of patch activation provided by an embodiment of the present invention; 
         FIG. 8  is a schematic diagram of function units of an embodiment of a multi-core online patching apparatus provided by the present invention; and 
         FIG. 9  is a schematic diagram of other function units of an embodiment of a multi-core online patching apparatus provided by the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In order to clearly illustrate how to map all patch data to a patch area of a shared memory, referring to  FIG. 2 , dividing of a physical address of the patch area is illustrated first. In the present invention, the physical address of the patch area is divided into three successive parts: a shared area, a private area, and a backup area. 
     The shared area includes shared code segments and a shared data segment, where the shared code segments are used to store shared codes of patches and read-only data segments in patch codes, and the shared data segment is used to store the shared global variables defined in the patches. The shared area of the patches is mapped by way of a direct memory address, that is, when a core reads data, the core obtains the data directly from the memory, not through a cache bus. 
     The private area is evenly divided into multiple private data segments according to the number of cores. Initial addresses of each private data segment are aligned according to the size of a Cache Line (the minimum unit of Cache), and each private data segment is used to store the private global variables defined in the patches. The patch private area is mapped by way of a variable address specified by a user, that is, the patch private area may be mapped by using a mapping mode of a cache bus access address or by using a mapping mode of a direct memory address. 
     The backup area is used to back up a function instruction of a core private memory and core private data, and used for self-restoring of a core initialized patch status. 
     The following describes the technical solutions of the present invention clearly and completely with reference to accompanying drawings. 
     As shown in  FIG. 3 , an embodiment of a multi-core online patching method provided by the present invention includes: 
     S 11 : Separate shared global variables and private global variables defined in a patch. 
     In order to ensure that access of the private global variables in the patch are free from influence, the embodiment of the present invention adopts the following defining forms for the private global variables defined in the patch. 
     The private global variables in the patch are defined as structure variables, and a size of a structure is a size of a private data segment of each core in a patch area; after defining member variables of the structure variables is completed, the residual space is segmented by using magic numbers, where data before magic numbers is valid data. Therefore, when extracting data segments, a patch tool searches for the magic numbers, and extracts only the valid data as the core private data; when a patch file is written, the pragma programming manner in the prior art may be used to place the shared global variables and the private global variables in different data segments. 
     S 12 : Map the shared global variables to a shared data segment in a patch area by using a mapping mode of a direct memory address, and map the private global variables to private data segments in the patch area by using a mapping mode of a variable address specified by a user. 
     The mapping of the private global variables by using a mapping mode of a variable address specified by a user specifically may be: extracting the valid data of the private global variables, and according to the size of the defined structure, mapping the valid data to the private data segments of each core in the patch area by using a mapping mode of a direct memory address or by using a mapping mode of a cache bus access address. 
     When the patch tool parses the data segments, if the data segments are shared global variables, mapping is performed according to a direct memory address; if the data segments are private global variables, mapping is performed according to variable addresses specified by a user, and magic numbers are searched in the data segments, the valid data before the magic numbers is recorded in the patch file, and the size of the valid data is added to available initial address of the private data segments of each core as an initial address of available private data segments next time, for being used in patch making next time. 
     If a patch is made for the first time, information of a patch area is obtained from configuration files, or addresses of code segments and data segments in patch making this time are obtained from patch files. According to the used addresses of valid data that are accumulated, the initial address in patch making next time is located, and the multiplexing of patch data segment space is implemented. 
     It can be seen that, by separating the shared global variables and the private global variables defined in the patch, mapping the shared global variables to the shared data segments in the patch area by using a mapping mode of a direct memory address, and mapping the private global variables to the private data segments in the patch area by using a mapping mode of a variable address specified by a user, all the patch data may be mapped to the patch area of a shared memory; besides, because different mapping manners are adopted in different variable types, and thereby the consistency of cache maintained by software is implemented, and cache conflicts are avoided. 
     Furthermore, the multi-core online patch method provided by the embodiment of the present invention may further include: backing up a function instruction of a core private memory and core private data to a data backup area in the patch area. 
     Therefore, when a patch management end performs a patch loading operation, the core private data, apart from loading to the private data segments of each core of the corresponding patch area, further needs to be loaded to the data backup area in the patch area for one time, so that after a single core is reset, the private data can also be restored when the patch status is restored. 
     Referring to the mapping situation of the patch area in  FIG. 4  to  FIG. 6 , the first line in  FIG. 4  describes a use situation of an external display after a patch is loaded for several times in a patch area; the second line of  FIG. 4  describes the actual use situation after a patch is loaded for several times in a patch area, where the part with darker gray is the valid data actually used by private data segments;  FIG. 5  describes a new patch that needs to be loaded, the space displayed above each segment is the size defined in each segment of an actual patch file; and  FIG. 6  is an actual use situation of the patch area after a new patch has been loaded. It can be seen from  FIG. 4  to  FIG. 6 , for the private global variables, when performing loading, the patch management end extracts only their valid data, and according to the defined size of the variables, loads the valid data to the private data segments and the data backup area of each core in the patch area. By defining the private global variables as structure variables, and using magic numbers, the defined size and the maintained size of the private global variables are separated from each other. 
     In an environment of a multi-core CPU, a cache is maintained by hardware, and because of the limitation of hardware memory characteristics, a master CPU core must be writable for all code segments and requires a master core to complete the operation process of a patch, and the master core must be fixed. When a certain core is abnormal, for example, is dead, none of the patching function operations can be completed, and all the CPUs need to be reset to implement the patching operation. For a multi-core digital signal processor (DSP) of telecom-grade software, the cache is maintained by software, each core has its own private memory. To implement that a certain DSP core can implement the patching function when the certain DSP core is abnormal, and after the abnormal core is reset, the certain DSP core can self-restore to the patch status. Therefore, with the multi-core online patch method provided by the embodiments of the present invention, the synchronous mask table needs to be processed as follows: 
     When the patch is initialized, a synchronous mask table with the same image is configured for all cores; when a certain core in the multiple cores is abnormal, if the abnormal core exists in the synchronous mask table, a synchronous mask flag of the abnormal core is removed from the synchronous mask table; after the abnormal core is reset, the patch status is restored according to the data backup area in the patch area, and the removed synchronous mask flag is re-added to the synchronous mask table after the patch status is restored on the abnormal core successfully. So when the patch is activated, the operation core of the multi-core DSP initiates a synchronization event to an online slave core according to the latest synchronous mask table. 
     The patch activation is a process that an online patch takes effect, and the basic principle of the online patch activation is to replace an instruction at the entrance of a primary function (a to-be-patched function) with a skip instruction, and skip a program invoking the primary function to a patch function in the patch area through the skip instruction to be executed, which relates to a core synchronous operation. In order to implement that a certain core can still implement the patching function in a case that the certain core is abnormal, when the patch is activated, the operation core may initiate the synchronization event to an online slave core according to the latest synchronous mask table. 
     Referring to  FIG. 7 , the operation process of the patch activation according to an embodiment of the present invention is specifically as follows: 
     S 21 : An operation core obtains information of a function that needs to be replaced. 
     The operation core obtains patch function information according to the patch that needs to be activated, where the obtained information includes: a primary function address and an address of a patch function in the patch area. 
     S 22 : The operation core sets a temporary memory to transfer inter-core information. 
     The operation core applies for a segment of a temporary memory to deliver inter-core information, where the delivered information includes: information such as the number of functions needs to be invalid, the data segments corresponding to a function address and the function, and the number of the functions in the core private memory and the corresponding skip instruction. 
     S 23 : The operation core initiates synchronization according to a core online situation. 
     The operation core obtains core online situation according to the latest synchronous mask table, initiates the synchronization event to the corresponding slave core, and then enters a synchronous wait status. After receiving the synchronization event, the online slave core enters the synchronous status. 
     S 24 : During the synchronization, the operation core and the slave core execute their respective synchronous operations. 
     The operation core executes the replacement of the shared memory skip instruction, saves the function information in the core private memory, and then waits for the end of the slave core operation. 
     The slave core closes interruption and endless loop, and waits for the end of the operation of the operation core, then invalidates an instruction Cache and a data Cache that correspond to a share memory, executes the replacement of the skip instruction of a core private memory, and moves private data to this core. 
     S 25 : The synchronization ends, the operation core and the slave core execute respective services. 
     S 26 : Process the abnormal synchronization. 
     If the slave core is abnormal in the stage of the patching operation, and not involved in the synchronous operation, the synchronous mask flag thereof is removed from the synchronous mask table before the abnormal core is reset, and the backup area in the patch area is read to restore to the patch status after the abnormal core is reset, and the synchronous mask flag thereof is re-added to the synchronous mask table after the patch status is restored on the abnormal core successfully. 
     To sum up, in the multi-core online patching method provided by the embodiments of the present invention, by defining the private global variables as the structure variables, it can be ensured that the access performance of the private global variables in the patch is free from influence; by separating the shared global variables and the private global variables defined in the patch and adopting different variable types for different mapping manners, all the patch data can be mapped to the patch area of the shared memory, and the consistency of the cache maintained by software may be implemented and cache conflicts may be avoided. Furthermore, by backing up the function instruction of the core private memory and the core private data, the abnormal core can self-restore to the patch status according to the data backup area in the patch area after the abnormal core is reset; by processing the synchronous mask table when the patch is initialized, when the patch is activated, the operation core may initiate the synchronization event to the online slave core according to the latest synchronous mask table, and can implement that the patching operation can still be executed when the certain core with the same image is abnormal. 
     Therefore, the embodiments of the present invention solve multi-core patching problems of scenes such as hardware does not support address mapping, hardware does not maintain the consistency of the cache, and an application program needs to use the private global variables and the shared global variables at the same time. Besides, the embodiments of the present invention further implement that when a certain core is abnormal, there is no need to reset all the cores to perform the patching operation, and further implement the function of patch status self-restoring after the certain core is reset. 
     It should be understood that, the embodiment of the present invention is not only applicable to the multi-core DSP system of telecom-grade software, but also applicable to all multi-core processors without the MMU mapping function. 
     Corresponding to the embodiments of the multi-core online patch method of the present invention, referring to  FIG. 8 , the present invention further provides an embodiment of a multi-core online patch apparatus, including: a variable separation unit  81  configured to separate shared global variables and private global variables defined in a patch; and a mapping unit  82  configured to map the shared global variables to a shared data segment in a patch area by using a mapping mode of a direct memory address, and map the private global variables to private data segments in the patch area by using a mapping mode of a variable address specified by a user. 
     The variable separation unit  81  includes: a structure defining module configured to define the private global variables in the patch as structure variables, where a size of a structure is a size of a private data segment that is of each core and in the patch area; a magic number segmentation module configured to, after completing defining member variables of the structure variables, segment the remaining space by using a magic number, where data before the magic number is valid data; and a placing module configured to, when a patch file is written, place the shared global variables and the private global variables in the patch in different data segments. 
     The variable separation unit  81  separates the shared global variables and the private global variables defined in the patch, and the mapping unit  82  maps the shared global variables to the shared data segment in the patch area by using a mapping mode of a direct memory address and maps the private global variables to the private data segments in the patch area by using a mapping mode of a variable address specified by a user, thereby mapping all patch data to the patch area of a shared memory. Because different mapping manners are adopted for different variable types, the consistency of the cache maintained by software is also implemented, and cache conflicts are avoided. 
     Furthermore, referring to  FIG. 9 , the multi-core online patching apparatus of the embodiment of the present invention may further include: a backup unit  91  configured to back up a function instruction of a core private memory and core private data to a data backup area in the patch area. 
     Therefore, when a patch management end performs patch loading operation, for the core private data, apart from being loaded to the private data segments of each core of the corresponding patch area, the backup unit  91  further backs up the function instruction of the core private memory and the core private data to the data backup area in the patch area, and thereby the private data can also be restored when the patch status is restored. 
     Furthermore, still referring to  FIG. 9 , the multi-core online patching apparatus of the embodiment of the present invention may further include: a mask table processing unit  92  configured to, when the patch is initialized, configure a synchronous mask table with a same image for all cores, when a certain core in the multiple cores is abnormal, if the abnormal core exists in the synchronous mask table, remove a synchronous mask flag of the abnormal core from the synchronous mask table, after the abnormal core is reset, restore the abnormal core to a patch status according to the data backup area in the patch area, and re-add the removed synchronous mask flag to the synchronous mask table after the patch status is restored on the abnormal core successfully; and a synchronization unit  93  configured to, when the patch is activated, initiate, by an operation core, a synchronization event to an online slave core according to the latest synchronous mask table. 
     Therefore, after the mask table processing unit  92  processes the synchronous mask table when the patch is initialized, the synchronization unit  93  enables the operation core to initiate the synchronization event to the online slave core according to the latest synchronous mask table when the patch is activated, and that a certain core with the same image still can execute the patching operation can be implemented when the certain core is abnormal. 
     Persons of ordinary skill in the art should understand that functional units in the embodiments of the present invention may be integrated into a processing module, or each of the units may exist alone physically, or two or more units are integrated into a module. The integrated modules may be implemented in a form of hardware or may be implemented in a form of software functional modules. When being implemented in the form of software functional modules and sold or used as an independent product, the integrated modules may also be stored in a computer readable storage medium. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), and the like. 
     The foregoing embodiments are not intended to limit the present invention. For persons of ordinary skill in the art, any modification, equivalent replacement, and improvement made without departing from the principle of the present invention shall fall within the protection scope of the present invention.