Sharing data in a user virtual address range with a kernel virtual address range

• US 20060107020A1
• Filed: 11/17/2004
• Published: 05/18/2006
• Est. Priority Date: 11/17/2004
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Stillwell, Paul M. Jr., Saletore, Vikram A.
• Granted Patent: US 7,290,114 B2
• Time in Patent Office: Days
• US Class Current: 711/203
• CPC Class Codes: G06F 12/109 for multiple virtual address spaces, e.g. segmentation G06F12/1036 takes precedence
• CPC Class Codes: G06F 2212/656 Address space sharing

Abstract

Provided are a method, system, and program for sharing data in a user virtual address range with a kernel virtual address range. A user address in a user address space and length defining a user address range referencing physical locations in a memory are received. A determination is made of determining at least one page in the memory including the physical locations referenced by the user address range. For each determined page, one kernel address in a kernel address space is generated to reference the determined page, wherein at least one user address and at least one kernel address reference one page in the memory.

Claims

1. A method comprising:

receiving a user address in a user address space and length defining a user address range referencing physical locations in a memory;

determining at least one page in the memory including the physical locations referenced by the user address range; and

generating, for each determined page, one kernel address in a kernel address space to reference the determined page, wherein at least one user address and at least one kernel address reference one page in the memory.

2. The method of claim 1, wherein determining the at least one page further comprises:

setting a specified user address to the received user address;

determining a page referenced by the specified user address;

incrementing the specified user address by a page size; and

performing an additional iteration of the operations of determining the page and incrementing the specified user address if the incremented specified user address is less than or equal to the received user address plus the length.

3. The method of claim 2, wherein determining the page referenced by the specified address comprises:

determining an entry in a page table indicated in the user address, wherein the determined page is indicated in the determined entry in the page table.

4. The method of claim 3, wherein determining the entry in the page table comprises:

determining an entry in a directory table indicated in the user address, wherein the determined entry in the directory table references the page table.

5. The method of claim 1, wherein generating the kernel address for one determined page further comprises:

indicating in an available entry in a kernel page table a reference to the determined page, wherein the entry in the kernel page table is indicated in the generated kernel address.

6. The method of claim 5, wherein generating the kernel address for one determined page further comprises:

indicating in an available entry in a kernel directory table a reference to the kernel page table including the reference to the determined page, wherein the entry in the kernel directory table is indicated in the generated kernel address.

7. The method of claim 1, further comprising:

applying a lock to each determined page to prevent the page from being swapped from the memory to a lower level storage while the kernel address references the page.

8. The method of claim 1, wherein a driver executing in kernel space receives the user address and the length from an application executing in user space, wherein the driver determines the at least one page and generates one kernel address for each determined page and further performs:

returning to the application a handle identifying an association of the kernel address and user address referencing the page in the memory; and

using, with the application, the handle to call the driver to perform operations with respect to the memory locations referenced by the handle.

9. The method of claim 8, wherein the driver further performs:

receiving a request from the application with respect to the handle;

determining the kernel address identified by the handle; and

executing the received request from the application with respect to the determined kernel address.

10. The method of claim 9, wherein the request comprises a request to deregister the handle, wherein executing the received request comprises:

releasing the kernel address indicated by the handle.

11. The method of claim 1, further comprising:

indicating in a data structure an association of each determined page with each kernel address referencing the determined page;

determining whether a first page in the user address range is associated with one kernel address in the data structure; and

using the kernel address in the data structure associated with the first page in response to determining that the data structure indicates the kernel address for the first page, wherein generating one kernel address for each determined page following the first page further comprises generating one kernel address following the used kernel address indicated in the data structure for each page following the first page, and wherein the generated kernel addresses comprise a contiguous range of kernel addresses.

12. The method of claim 1, further comprising:

indicating in a data structure an association of each determined page with each kernel address referencing the determined page;

determining whether a first page in the user address range is associated with one kernel address in the data structure;

determining a last page in the user address range in response to determining that the first page is not associated with one kernel address in the data structure and in response to their being multiple pages referenced by the user address range;

determining whether a last kernel address to be generated for the last page matches the kernel address associated with the last page in the data structure in response to determining that the last page is associated with one kernel address in the data structure; and

returning an error in response to determining the last kernel address to be generated does not match the kernel address associated with the last page in the data structure.

13. The method of claim 12, wherein the kernel addresses are generated in response to determining that the last kernel address to be generated matches the kernel address associated with the last page in the data structure.

14. A system, comprising:

a memory having a kernel address space and a user address space;

a processor in communication with the memory;

code executed by the processor to perform operations, the operations comprising;

(i) receiving a user address in the user address space and length defining a user address range referencing physical locations in the memory;

(ii) determining at least one page in the memory including the physical locations referenced by the user address range; and

(iii) generating, for each determined page, one kernel address in the kernel address space to reference the determined page, wherein at least one user address and at least one kernel address reference a one page in the memory.

15. The system of claim 14, wherein determining the at least one page further comprises:

setting a specified user address to the received user address;

determining a page referenced by the specified user address;

incrementing the specified user address by a page size; and

performing an additional iteration of the operations of determining the page and incrementing the specified user address if the incremented specified user address is less than or equal to the received user address plus the length.

16. The system of claim 15, wherein determining the page referenced by the specified address comprises:

determining an entry in a page table indicated in the user address, wherein the determined page is indicated in the determined entry in the page table.

17. The system of claim 16, wherein determining the entry in the page table comprises:

determining an entry in a directory table indicated in the user address, wherein the determined entry in the directory table references the page table.

18. The system of claim 14, wherein generating the kernel address for one determined page further comprises:

indicating in an available entry in a kernel page table a reference to the determined page, wherein the entry in the kernel page table is indicated in the generated kernel address.

19. The system of claim 18, wherein generating the kernel address for one determined page further comprises:

indicating in an available entry in a kernel directory table a reference to the kernel page table including the reference to the determined page, wherein the entry in the kernel directory table is indicated in the generated kernel address.

20. The system of claim 14, wherein the operations performed by the processor further comprise:

applying a lock to each determined page to prevent the page from being swapped from the memory to a lower level storage while the kernel address references the page.

21. The system of claim 14, wherein the operations performed by the processor further comprising:

maintaining a kernel space and user space;

an application the processor executes in the user space;

a driver the processor executes in the kernel space, wherein the driver receives the user address and the length from the application, and wherein the driver determines the at least one page and generates one kernel address for each determined page and further performs;

(i) returning to the application a handle identifying an association of the kernel address and user address referencing the page in the memory, wherein the application uses the handle to call the driver to perform operations with respect to the memory locations referenced by the handle.

22. The system of claim 21, wherein the driver executed by the processor further performs:

receiving a request from the application with respect to the handle;

determining the kernel address identified by the handle; and

executing the received request from the application with respect to the determined kernel address.

23. The system of claim 22, wherein the request comprises a request to deregister the handle, wherein executing the received request comprises:

releasing the kernel address indicated by the handle.

24. The system of claim 14, wherein the operations performed by the processor further comprise:

indicating in a data structure in the memory an association of each determined page with each kernel address referencing the determined page;

determining whether a first page in the user address range is associated with one kernel address in the data structure; and

using the kernel address in the data structure associated with the first page in response to determining that the data structure indicates the kernel address for the first page, wherein generating one kernel address for each determined page following the first page further comprises generating one kernel address following the used kernel address indicated in the data structure for each page following the first page, and wherein the generated kernel addresses comprise a contiguous range of kernel addresses.

25. The system of claim 14, wherein the operations performed by the processor further comprise:

indicating in a data structure in the memory an association of each determined page with each kernel address referencing the determined page;

determining whether a first page in the user address range is associated with one kernel address in the data structure;

determining a last page in the user address range in response to determining that the first page is not associated with one kernel address in the data structure and in response to their being multiple pages referenced by the user address range;

determining whether a last kernel address to be generated for the last page matches the kernel address associated with the last page in the data structure in response to determining that the last page is associated with one kernel address in the data structure; and

returning an error in response to determining the last kernel address to be generated does not match the kernel address associated with the last page in the data structure.

26. The system of claim 25, wherein the kernel addresses are generated in response to determining that the last kernel address to be generated matches the kernel address associated with the last page in the data structure.

27. An article of manufacture comprising a storage medium having stored therein instructions capable of being executed by a processor in communication with a memory to perform:

receiving a user address in a user address space and length defining a user address range referencing physical locations in a memory;

determining at least one page in the memory including the physical locations referenced by the user address range; and

generating, for each determined page, one kernel address in a kernel address space to reference the determined page, wherein at least one user address and at least one kernel address reference one page in the memory.

28. The article of manufacture of claim 27, wherein determining the at least one page further comprises:

setting a specified user address to the received user address;

determining a page referenced by the specified user address;

incrementing the specified user address by a page size; and

performing an additional iteration of the operations of determining the page and incrementing the specified user address if the incremented specified user address is less than or equal to the received user address plus the length.

29. The article of manufacture of claim 28, wherein determining the page referenced by the specified address comprises:

determining an entry in a page table indicated in the user address, wherein the determined page is indicated in the determined entry in the page table.

30. The article of manufacture of claim 29, wherein determining the entry in the page table comprises:

determining an entry in a directory table indicated in the user address, wherein the determined entry in the directory table references the page table.

31. The article of manufacture of claim 27, wherein generating the kernel address for one determined page further comprises:

indicating in an available entry in a kernel page table a reference to the determined page, wherein the entry in the kernel page table is indicated in the generated kernel address.

32. The article of manufacture of claim 31, wherein generating the kernel address for one determined page further comprises:

indicating in an available entry in a kernel directory table a reference to the kernel page table including the reference to the determined page, wherein the entry in the kernel directory table is indicated in the generated kernel address.

33. The article of manufacture of claim 27, wherein the instructions are capable of being executed to further perform:

applying a lock to each determined page to prevent the page from being swapped from the memory to a lower level storage while the kernel address references the page.

34. The article of manufacture of claim 27, wherein the storage medium further includes a driver and an application executed by the processor, wherein the instructions are capable of being executed by the processor to further perform:

providing a kernel space and a user space, wherein the driver executing in the kernel space receives the user address and the length from the application executing in the user space, wherein the driver determines the at least one page and generates one kernel address for each determined page;

returning to the application, by the driver, a handle identifying an association of the kernel address and user address referencing the page in the memory; and

using, by the application, the handle to call the driver to perform operations with respect to the memory locations referenced by the handle.

35. The article of manufacture of claim 34, wherein the driver is executed by the processor to further perform:

receiving a request from the application with respect to the handle;

determining the kernel address identified by the handle; and

executing the received request from the application with respect to the determined kernel address.

36. The article of manufacture of claim 35, wherein the request comprises a request to deregister the handle, wherein executing the received request comprises:

releasing the kernel address indicated by the handle.

37. The article of manufacture of claim 27, wherein the instructions are capable of being executed to further perform:

indicating in a data structure in the memory an association of each determined page with each kernel address referencing the determined page;

determining whether a first page in the user address range is associated with one kernel address in the data structure; and

using the kernel address in the data structure associated with the first page in response to determining that the data structure indicates the kernel address for the first page, wherein generating one kernel address for each determined page following the first page further comprises generating one kernel address following the used kernel address indicated in the data structure for each page following the first page, and wherein the generated kernel addresses comprise a contiguous range of kernel addresses.

38. The article of manufacture of claim 27, wherein the instructions are capable of being executed to further perform:

indicating in a data structure an association of each determined page with each kernel address referencing the determined page;

determining whether a first page in the user address range is associated with one kernel address in the data structure;

determining a last page in the user address range in response to determining that the first page is not associated with one kernel address in the data structure and in response to their being multiple pages referenced by the user address range;

determining whether a last kernel address to be generated for the last page matches the kernel address associated with the last page in the data structure in response to determining that the last page is associated with one kernel address in the data structure; and

returning an error in response to determining the last kernel address to be generated does not match the kernel address associated with the last page in the data structure.

39. The article of manufacture of claim 38, wherein the kernel addresses are generated in response to determining that the last kernel address to be generated matches the kernel address associated with the last page in the data structure.