Accessing private data about the state of a data processing machine from storage that is publicly accessible

• US 9,087,000 B2
• Filed: 03/15/2013
• Issued: 07/21/2015
• Est. Priority Date: 11/26/2003
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Robinson, Scott H., Espinosa, Gustavo P., Bennett, Steven M.
• Primary Examiner(s): Yalew, Fikremariam A
• Application Number:
  US13/836,863
• Publication Number:
  US 20130275772A1
• Time in Patent Office: 858 Days
• Field of Search: 713189-193
• US Class Current: 1/1
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 21/71 to assure secure computing or processing of information
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00

Abstract

According to an embodiment of the invention, a method for operating a data processing machine is described in which data about a state of the machine is written to a location in storage. The location is one that is accessible to software that may be written for the machine. The state data as written is encoded. This state data may be recovered from the storage according to a decoding process. Other embodiments are also described and claimed.

Claims

1. A method for operating a data processing machine, comprising:

applying by a processor an encoding process to private-state data of said processor, where the private-state data captures a state of the processor;

writing, to a location in storage, said encoded private-state data, the location being one that is accessible to software written for the processor; and

reading by the software the encoded private-state data from the storage using an instruction that causes the processor to decode the encoded private-state data and store the decoded private-state data in a private-state area accessible to software only by using the instruction;

wherein the private-state data refers to one of content of an internal register of the processor that is not explicitly identified in an instruction manual for the processor, and content of an internal register of the processor that is explicitly identified in the instruction manual but is stored in one of a format and a location that is not explicitly identified in the instruction manual.

2. The method of claim 1 wherein the encoding process is to thwart an attempt at recovering the private-state data from the storage by a second process different from the decoding process.

3. The method of claim 1 wherein the encoding process is configured to cause an author of the software to apply, in writing said software, a technique prescribed by a manufacturer of the processor for accessing the private-state data from storage rather than circumventing said technique.

4. The method of claim 1 wherein the private-state data is written to one of a publicly accessible location in a register file of the processor, cache, and memory.

5. The method of claim 1 wherein during the encoding process the location of written contents of a given internal register of the processor changes arbitrarily at least once, while repeating the applying and the writing.

6. The method of claim 1 wherein during the encoding process a storage format of written contents of a given internal register of the processor changes arbitrarily at least once between big-endian and little-endian, while repeating the applying and the writing.

7. The method of claim 1 wherein during the encoding process a cipher is applied to the contents of a given internal register to produce an encoded value which is then written to the location in storage.

8. The method of claim 1 further comprising storing recovered state data in a private storage of the processor.

9. An apparatus for operating a data processing machine, comprising:

a data processing machine having a private internal state, the internal state to change as the data processing machine executes instructions provided to itself as part of a program, wherein the data processing machine is to encode data about the internal state and write the encoded state data to a location in a storage unit, wherein the location is readable by an instruction set architecture of the data processing machine using an instruction that causes the data processing machine to decode the encoded state data and store the decoded state data in a private state area accessible to software only by using the instruction;

wherein the data about the internal state refers to one of content of an internal register of the data processing machine that is not explicitly identified in an instruction manual for the data processing machine, and content of an internal register of the data processing machine that is explicitly identified in the instruction manual but is stored in one of a format and a location that is not explicitly identified in the instruction manual.

10. The apparatus of claim 9 wherein the data processing machine is a processor that has a special read micro-operation, to be used when the processor is to recover said state data from the storage unit.

11. The apparatus of claim 10 wherein the processor further includes an internal cache and is to also write the encoded state data to a public location in the cache.

12. The apparatus of claim 10 wherein the processor is to recover the state data and write the recovered state data to a private location in the processor.

13. The apparatus of claim 10 wherein the processor is to recover the state data and configure itself with the recovered state data in preparation for resuming execution of a suspended task.

14. The apparatus of claim 10 wherein the processor comprises a manufacturer-defined instruction that, when executed by the processor, recovers the state data from the storage unit.

15. The apparatus of claim 9 wherein the data processing machine is a processor for which a special micro-operation is defined for accessing the encoded state data from the storage unit, and wherein the processor further comprises an address obfuscation unit to receive an address value associated with given state data of the processor, the address value having been derived from a dispatch of the special micro-operation, the obfuscation unit to provide an encoded, physical address value that points to the actual location in the storage unit where the given state data is stored.

16. The apparatus of claim 9 wherein the data processing machine is a processor for which a hardware control signal is defined for accessing the encoded data from the storage unit, and wherein the processor further comprises an internal cache, a data conversion unit to receive a data value from the internal cache as a result of a cache hit derived from the hardware control signal, the conversion unit to decode the data value into actual state data of the processor.

17. A computer system comprising:

a processor; and

a main memory communicatively coupled to the processor and having a public region designated to store the processor'"'"'s private-state data in encoded form, the instruction set architecture of the processor including an instruction to decode and read said the private-state data from the public region;

wherein the private-state data refers to one of content of an internal register of the processor that is not explicitly identified in an instruction manual for the processor, and content of an internal register of the processor that is explicitly identified in the instruction manual but is stored in one of a format and a location that is not explicitly identified in the instruction manual.

18. The system of claim 17 wherein the processor encodes the private-state data prior to storing it to the public region.

19. The system of claim 17 wherein the processor decodes a value read from the public region prior to using it.

20. The system of claim 17 wherein the processor further includes an internal storage unit in which a public region is designated to store a copy of said private-state data in encoded form.

21. The system of claim 20 wherein the internal storage unit is one of a cache and a register file.

22. The system of claim 20 wherein a private region is designated in the internal storage unit to store said private-state data in unencoded form.

23. The system of claim 20 further comprising a system chipset communicatively coupling the processor to the main memory.

24. A method for operating a data processing machine, comprising:

encoding private state data about a state of the data processing machine; and

writing, to a location in storage, the encoded private state data, the location being readable to software that is running on the data processing machine using an instruction that causes the data processing machine to decode the encoded private state data and store the decoded private state data in a private state area accessible to software only by using the instruction;

wherein the private state data refers to one of content of an internal register of the data processing machine that is not explicitly identified in an instruction manual for the data processing machine, and content of an internal register of the data processing machine that is explicitly identified in the instruction manual but is stored in a format or location that is not explicitly identified in the instruction manual.

25. The method of claim 24, wherein the encoding comprises ciphering a value of the private state data to yield said encoded private state data.

26. The method of claim 24, wherein the private state data about the state of the data processing machine is one of a register value and a value from the storage.

27. The method of claim 24, wherein the encoding comprises address encoding to obfuscate an address value of the private state data.

28. The method of claim 24 further comprising recovering the private state data from the storage according to a decoding process.

29. The method of claim 28 wherein the recovering comprises reading a plurality of values from memory;

and combining the read plurality of values to form a single unencoded value of said private state data.

30. The method of claim 28 wherein the recovering comprises reading a plurality values from one or more discontiguous locations of memory;

combining the read plurality values to form a single value; and

decoding the single value to form an unencoded value of said private state data.

31. The method of claim 28 further comprising storing the recovered private state data in a private storage of the data processing machine.