Protecting memory by containing pointer accesses

• US 20080140968A1
• Filed: 12/12/2006
• Published: 06/12/2008
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Jacobson, Quinn A., Doshi, Kshitij A.
• Granted Patent: US 7,761,676 B2
• Time in Patent Office: Days
• US Class Current: 711/163
• CPC Class Codes: G06F 12/1466 Key-lock mechanism

Abstract

In one embodiment, the present invention includes a method for associating a first identifier with a first pointer that points to a first object in a memory. The first identifier may correspond to a value in a segment of a map array for a location of the first object in the memory. Other embodiments are described and claimed.

Claims

1. A method comprising:

associating a first identifier with a first pointer that points to a first object in a memory, the first identifier corresponding to a value in a segment of a map array for a location of the first object in the memory.

2. The method of claim 1, further comprising arbitrarily assigning values in the map array.

3. The method of claim 1, further comprising organizing the map array into a plurality of segments, wherein each segment is to correspond to a block of the memory.

4. The method of claim 3, further comprising associating a common identifier to a pointer that points to an object that consumes at least a portion of two blocks of the memory, and wherein at least two of the plurality of segments of the map array are to store the common identifier.

5. The method of claim 1, further comprising associating the first identifier with the first pointer by writing the first identifier in a portion of a virtual address of the first pointer.

6. The method of claim 1, further comprising associating the first identifier with the first pointer by encoding the first identifier into an instruction that references the first object.

7. The method of claim 6, further comprising encoding the first identifier by incorporation of an absolute color or a relative color into the instruction.

8. The method of claim 1, further comprising determining if a pointer that points to the first object is associated with the first identifier.

9. The method of claim 8, further comprising preventing access to the first object by the pointer if the pointer is not associated with the first identifier.

10. An apparatus comprising:

a map including a plurality of elements each to store a value for a corresponding block of a memory, wherein the value is to be arbitrarily generated and is to be used to determine access permission to the corresponding block of the memory.

11. The apparatus of claim 10, further comprising a storage to store at least a portion of the map, wherein the portion is to accelerate determination of the access permission.

12. The apparatus of claim 11, wherein the storage comprises a color lookaside buffer (CLB).

13. The apparatus of claim 12, wherein the CLB is to store a plurality of entries, each of the entries to include a portion of the map for a region of the memory including a plurality of blocks.

14. The apparatus of claim 12, further comprising a translation lookaside buffer (TLB) to store virtual address to physical address translations.

15. The apparatus of claim 14, wherein the CLB is to be maintained incoherently with the TLB.

16. The apparatus of claim 10, wherein the map is to store a first value in an element if access to the corresponding block of the memory is to be unlimited, and to store a second value in the element if no access to the corresponding block of the memory is to be permitted.

17. The apparatus of claim 10, further comprising an access validator to determine if an identifier portion of a pointer matches the value stored in an element of the map, wherein the pointer points to a block of the memory corresponding to the element of the map.

18. The apparatus of claim 17, wherein the access validator is to prevent access to the corresponding block of the memory if a mismatch occurs.

19. A machine-readable medium having stored thereon instructions, which if executed by a machine cause the machine to perform a method comprising:

determining if a first portion of a pointer matches a value stored in a location of a map that corresponds to a block of memory pointed to by the pointer.

20. The machine-readable medium of claim 19, wherein the method further comprising allowing access to the block of memory if a match occurs, otherwise preventing the access.

21. The machine-readable medium of claim 19, wherein the method further comprises:

searching a color lookaside buffer (CLB) for a portion of the map associated with the pointer; and

obtaining and storing the portion of the map in the CLB if the portion of the map is not present in the CLB.

22. The machine-readable medium of claim 19, wherein the method further comprises accessing a vector associated with the location of the map, wherein the vector includes a plurality of elements each having an indicator to indicate whether a portion of the corresponding block of memory includes a beginning of an object.

23. The machine-readable medium of claim 19, wherein the method further comprises encoding the value in an instruction that is to access the block of memory.

24. The machine-readable medium of claim 19, wherein the method further comprises dynamically modifying a size of the location of the map and the corresponding block of memory.

25. A system comprising:

a map having a plurality of locations each to store an identifier to control access to a corresponding block of a memory;

a vector associated with at least one of the locations of the map, wherein the vector includes a plurality of portions each to identify if a corresponding portion of the corresponding block of the memory is to include a new object; and

a dynamic random access memory (DRAM) coupled to the map, the DRAM comprising the memory.

26. The system of claim 25, further comprising a color lookaside buffer (CLB) to store a plurality of entries, each of the entries to include a portion of the map for a region of the memory including a plurality of blocks.

27. The system of claim 26, further comprising a walker coupled to the CLB to obtain a portion of the map and store the portion in the CLB if at least a portion of a pointer does not hit in the CLB.

28. The system of claim 25, further comprising a control register to store a base address for the map.

29. The system of claim 25, wherein each of the plurality of portions of the vector is to store a first value if the corresponding portion of the corresponding block of the memory includes an object boundary, and a second value if the corresponding portion does not include an object boundary.