Global variable migration via virtual memory overlay technique for multi-version asynchronous dynamic software update

• US 10,528,479 B2
• Filed: 06/02/2017
• Issued: 01/07/2020
• Est. Priority Date: 06/02/2017
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Wang, Kai-Ting Amy, Wu, Peng
• Primary Examiner(s): Rivera, Anibal
• Application Number:
  US15/612,602
• Publication Number:
  US 20180349289A1
• Time in Patent Office: 949 Days
• CPC Class Codes: G06F 12/0261 using reference counting
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 12/1027 using associative or pseudo-associative address translation means, e.g. translation look-aside buffer [TLB]
• CPC Class Codes: G06F 12/1036 for multiple virtual address spaces, e.g. segmentation G06F12/1045 takes precedence
• CPC Class Codes: G06F 2212/656 Address space sharing
• CPC Class Codes: G06F 2212/657 Virtual address space management
• CPC Class Codes: G06F 8/65 Updates security arrangements therefor G06F21/57
• CPC Class Codes: G06F 9/4405 Initialisation of multiprocessor systems
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

System and method for managing migration of global variables on processing system during live program updates, including creating a shared data segment is created in a physical memory of the processing system, binding a logical address space of a first global variable data segment for a first version of a program to a physical address of the shared data segment, and binding a logical address space for a second global variable data segment for an update version of the program to the physical address of the shared data segment. The first global variable data segment and the second global variable data segment exist concurrently and each map to common global variables stored in the shared data segment.

Claims

1. A method for managing migration of global variables on a processing system during live program updates, comprising:

creating a shared data segment in a physical memory of the processing system;

when a first version of a program is loaded by the processing system;

allocating a logical address space for a first global variable data segment for a first version of a program and binding the first global variable data segment to the shared data segment;

assigning physical addresses in the shared data segment for a plurality of global variables referenced in the first version of the program; and

including virtual addresses in the first global variable data segment that map to the plurality of global variables;

when an update version of the program is subsequently loaded by the processing system and is executed concurrently with the first version;

allocating a logical address space for a second global variable data segment for the update version of the program and binding the second variable data segment to the shared data segment;

assigning physical addresses in the shared data segment for added global variables that are referenced in the update version and not the first version;

including virtual addresses in the second global variable data segment that map to the physical addresses in the shared data segment for common global variables referenced in both the first version and the update version, and

including virtual addresses in the second global variable data segment that map to the physical addresses in the shared data segment for the added global variables;

wherein the first global variable data segment for the first version of the program and the second global variable data segment for the update version of the program exist concurrently, and the first and second global variable data segments each map to the common global variables stored in the shared data segment.

2. The method of claim 1 comprising, when the update version is loaded, including padding in virtual addresses of the second global variable data segment that map to the physical addresses of dropped global variables that are referenced in the first version but not the update version.

3. The method of claim 2 comprising:

generating, for the first version, a first linker-map that identifies the global variables referenced in the first version and the virtual addresses that map to the global variables;

determining, based on the first linker-map;

(i) the added global variables that are referenced in the update version and not the first version;

(ii) the common global variables referenced in both the first version and the update version; and

(iii) the dropped global variables that are referenced in the first version but not the update version.

4. The method of claim 1 wherein a first process thread executing the first version is active concurrently with a second process thread executing the second version on the processing system, wherein the first process thread accesses the plurality of global variables, stored in the shared data segment, referenced in the first version, and the second process thread accesses the common global variables and the added global variables, stored in the shared data segment, referenced in the update version.

5. The method of claim 4 wherein the first process thread keeps accessing the plurality of global variables without quiescing when the second process thread accesses the common global variables and the added global variables.

6. The method of claim 1 wherein creating the shared data segment comprises obtaining a shared memory file descriptor for the shared data segment.

7. The method of claim 6 wherein binding the first global variable data segment to the shared data segment comprises memory mapping the first global variable data segment to the shared data segment based on the shared memory file descriptor, and binding the second global variable data segment to the shared data segment comprises memory mapping the first second variable data segment to the shared data segment based on the shared memory file descriptor.

8. The method of claim 2 further comprising adding new variables in the padding when loading a version subsequent to the update version.

9. A processing system configured to manage migration of global variables during live program updates, comprising:

a processing device;

a memory associated with the processing device;

a non-transient storage for storing instructions that when loaded to the memory and executed by the processing device cause the processing device to;

create a shared data segment in the memory;

when a first version of a program is loaded by the processing system;

allocate a logical address space for a first global variable data segment for a first version of a program and bind the first global variable data segment to the shared data segment;

assign physical addresses in the shared data segment for a plurality of global variables referenced in the first version of the program; and

include virtual addresses in the first global variable data segment that map to the plurality of global variables;

when an update version of the program is subsequently loaded by the processing system and is executed concurrently with the first version;

allocate a logical address space for a second global variable data segment for an update version of the program and bind the second global variable data segment to the shared data segment;

assign physical addresses in the shared data segment for added global variables that are referenced in the update version and not in the first version;

include virtual addresses in the second global variable data segment that map to the physical addresses in the shared data segment for common global variables referenced in both the first version and the update version, and

include virtual addresses in the second global variable data segment that map to the physical addresses in the shared data segment for the added global variables;

wherein the first global variable data segment for the first version of the program and the second global variable data segment for the update version of the program exist concurrently, and the first and second global variable data segments each map to the common global variables stored in the shared data segment.

10. The processing system of claim 9 wherein the stored instructions cause the processing device to, when the update version is loaded, include padding in virtual addresses of the second global variable data segment that map to the physical addresses of dropped global variables that are referenced in the first version but not the update version.

11. The processing system of claim 10 wherein the stored instructions cause the processing device to:

generate, for the first version, a first linker-map that identifies the global variables referenced in the first version and virtual addresses of the global variables;

determine, based on the first linker-map;

(i) the added global variables that are referenced in the update version and not the first version;

(ii) the common global variables referenced in both the first version and the update version; and

(iii) the dropped global variables that are referenced in the first version but not the update version.

12. The processing system of claim 9 wherein a first process thread executing the first version is active concurrently with a second process thread executing the second version on the processing system, wherein the first process thread accesses the plurality of global variables, stored in the shared data segment, referenced in the first version, and

the second process thread accesses the common global variables and the added global variables, stored in the shared data segment, referenced in the update version.

13. The processing system of claim 9 wherein the stored instructions cause the processing device to obtain a shared memory file descriptor for the shared data segment.

14. The processing system of claim 13 wherein the stored instructions cause the processing device to:

bind the first global variable data segment to the shared data segment by memory mapping the logical address space to the shared data segment based on the shared memory file descriptor, and bind the second global variable data segment to the shared data segment by memory mapping the logical address space to the shared data segment based on the shared memory file descriptor.

15. The processing system of claim 10 wherein the stored instructions cause the processing device to, add new variables in the padding when loading a version subsequent to the update version.

16. A computer program product comprising a non-transient storage medium storing instructions managing migration of global variables on a processing system comprising instructions to cause a processing device to:

create a shared data segment in a physical memory of the processing system;

when a first version of a program is loaded by the processing system;

allocate a logical address space for a first global variable data segment for a first version of a program and bind the first global variable data segment to the shared data segment;

assign physical addresses in the shared data segment for a plurality of global variables referenced in the first version of the program; and

include virtual addresses in the first global variable data segment that map to the plurality of global variables;

when an update version of the program is subsequently loaded by the processing system and is executed concurrently with the first version;

allocate a logical address space for a second global variable data segment for an update version of the program and bind the second global variable data segment to the shared data segment;

assign physical addresses in the shared data segment for added global variables that are referenced in the update version and not in the first version;

include virtual addresses in the second global variable data segment that map to the physical addresses in the shared data segment for common global variables referenced in both the first version and the update version, and

include virtual addresses in the second global variable data segment that map to the physical addresses in the shared data segment for the added global variables;

wherein the first global variable data segment for the first version of the program and the second global variable data segment for the update version of the program exist concurrently, and the first and second global variable data segments each map to the common global variables stored in the shared data segment.

17. The computer program product of claim 16 wherein the stored instructions cause the processing device to, when the update version is loaded, include padding in virtual addresses of the second global variable data segment that map to the physical addresses of dropped global variables that are referenced in the first version but not the update version.

18. The computer program product of claim 17 wherein the stored instructions cause the processing device to:

generate, for the first version, a first linker-map that identifies the global variables referenced in the first version and virtual addresses of the global variables;

determine, based on the first linker-map;

(i) the added global variables that are referenced in the update version and not the first version;

(ii) the common global variables referenced in both the first version and the update version; and

(iii) the dropped global variables that are referenced in the first version but not the update version.

19. The computer program product of claim 16 wherein the stored instructions cause the processing device to:

obtain a shared memory file descriptor for the shared data segment;

bind the first global variable data segment to the shared data segment by memory mapping the logical address space to the shared data segment based on the shared memory file descriptor; and

bind the second global variable data segment to the shared data segment by memory mapping the logical address space to the shared data segment based on the shared memory file descriptor.

20. The computer program product of claim 16 wherein a first process thread executing the first version is active concurrently with a second process thread executing the second version on the processing system, wherein the first process thread accesses the plurality of global variables, stored in the shared data segment, referenced in the first version, and

the second process thread accesses the common global variables and the added global variables, stored in the shared data segment, referenced in the update version.