Microprocessor having internal secure memory

• US 8,838,924 B2
• Filed: 10/31/2008
• Issued: 09/16/2014
• Est. Priority Date: 05/24/2008
• Status: Active Grant

• Current Assignee: VIA Technologies Incorporated (VIA Technologies)
• Original Assignee: VIA Technologies Incorporated (VIA Technologies)
• Inventors: Henry, G. Glenn, Parks, Terry
• Primary Examiner(s): Parikh, Kalpit
• Application Number:
  US12/263,143
• Publication Number:
  US 20090292894A1
• Time in Patent Office: 2,146 Days
• Field of Search: 711/163, 713/166, 726/27
• US Class Current: 711/163
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 21/12 Protecting executable software
• CPC Class Codes: G06F 21/14 against software analysis or reverse engineering, e.g. by obfuscation
• CPC Class Codes: G06F 21/554 involving event detection and direct action
• CPC Class Codes: G06F 21/70 Protecting specific internal or peripheral components, in which the protection of a component leads to protection of the entire computer
• CPC Class Codes: G06F 21/71 to assure secure computing or processing of information
• CPC Class Codes: G06F 21/72 in cryptographic circuits
• CPC Class Codes: G06F 21/73 by creating or determining hardware identification, e.g. serial numbers
• CPC Class Codes: G06F 21/74 operating in dual or compartmented mode, i.e. at least one secure mode
• CPC Class Codes: G06F 21/82 Protecting input, output or interconnection devices

Abstract

An apparatus providing for a secure execution environment. The apparatus includes a microprocessor that is configured to execute non-secure application programs and a secure application program, where the non-secure application programs are accessed from a system memory via a system bus. The microprocessor has a non-secure memory and a secure volatile memory. The non-secure memory is configured to store portions of the non-secure application programs for execution by the microprocessor, where the non-secure memory is observable and accessible by the non-secure application programs and by system bus resources within the microprocessor. The secure volatile memory is configured to store the secure application program for execution by the microprocessor, where the secure volatile memory is isolated from the non-secure application programs and the system bus resources within the microprocessor. The secure application program is decrypted using a processor unique key and is written to the secure volatile memory.

Claims

1. An apparatus providing for a secure execution environment, comprising:

a microprocessor, coupled to a system bus, configured to execute non-secure application programs and a secure application program, wherein said non-secure application programs are accessed from a system memory via said system bus, and wherein said microprocessor is also configured to automatically transition to a degraded mode where only BIOS instructions are allowed to execute in order to allow for user input and the display of messages, said microprocessor comprising;

a non-secure memory, configured to store portions of said non-secure application programs for execution by the microprocessor, wherein said non-secure memory is observable and accessible by said non-secure application programs and by system bus resources within said microprocessor;

a secure volatile memory, configured to store said secure application program for execution by said microprocessor, wherein said secure volatile memory is isolated from said non-secure application programs and said system bus resources within said microprocessor, and wherein said secure application program is retrieved from a secure non-volatile memory over a private bus, decrypted using a processor unique key, and is written to said secure volatile memory;

a cryptographic unit, isolated from said system bus and disposed within execution logic in said microprocessor, configured to employ said processor unique key to decrypt said secure application program; and

a processor key register, coupled to said cryptographic unit, configured to store said processor unique key, wherein said processor key register can only be read by said cryptographic unit.

2. The apparatus as recited in claim 1, wherein said secure volatile memory comprises an instruction cache and a data cache for said secure application program.

3. The apparatus as recited in claim 1, wherein said secure volatile memory comprises a stack for storage and retrieval of the state of said microprocessor corresponding to said non-secure application programs.

4. The apparatus as recited in claim 1, wherein said secure application program accesses said secure volatile memory to read and write secure data by employing load and store instructions.

5. The apparatus as recited in claim 4, wherein said load and store instructions reference segment registers in address logic which are initialized upon entry into secure execution to point to said secure volatile memory instead of said system memory.

6. The apparatus as recited in claim 1, wherein said secure volatile memory comprises a 64-bit cache memory having 4096 locations, and wherein each of said locations comprises an internal attribute that completely isolates each of said locations.

7. The apparatus as recited in claim 1, further comprising:

SEM logic, coupled to said secure volatile memory and to address logic in said microprocessor, configured to disable virtual address translation by said address logic when said microprocessor is executing said secure application program.

8. The apparatus as recited in claim 7, wherein, upon execution of a secure mode enabled reset sequence by said microprocessor, said SEM logic initializes said secure volatile memory to random values.

9. A microprocessor apparatus, for executing secure code within a secure execution environment, the microprocessor apparatus comprising:

a secure non-volatile memory, coupled to a private bus, configured to store a secure application program; and

a microprocessor, coupled to said private bus, configured to execute non-secure application programs and said secure application program, wherein said non-secure application programs are accessed from a system memory via a system bus, and wherein said secure application program is accessed from said secure non-volatile memory, and wherein transactions over said private bus are isolated from said system bus and corresponding system bus resources within said microprocessor, and wherein said microprocessor is also configured to automatically transition to a degraded mode where only BIOS instructions are allowed to execute in order to allow for user input and the display of messages, said microprocessor comprising;

a non-secure memory, configured to store portions of said non-secure application programs for execution by said microprocessor, wherein said non-secure memory is observable and accessible by said non-secure application programs and by system bus resources within said microprocessor, and;

a secure volatile memory, configured to store said secure application program for execution by said microprocessor, wherein said secure volatile memory is isolated from said non-secure application programs and said system bus resources within said microprocessor, and wherein said secure application program is retrieved from said secure non-volatile memory, decrypted using a processor unique key, and is written to said secure volatile memory;

a cryptographic unit, isolated from said system bus and disposed within execution logic in said microprocessor, configured to employ said processor unique key to decrypt said secure application program; and

a processor key register, coupled to said cryptographic unit, configured to store said processor unique key, wherein said processor key register can only be read by said cryptographic unit.

10. The microprocessor apparatus as recited in claim 9, wherein said secure volatile memory comprises an instruction cache and a data cache for said secure application program.

11. The microprocessor apparatus as recited in claim 9, wherein said secure volatile memory comprises a stack for storage and retrieval of the state of said microprocessor corresponding to said non-secure application programs.

12. The microprocessor apparatus as recited in claim 9, wherein said secure application program accesses said secure volatile memory to read and write secure data by employing load and store instructions.

13. The microprocessor apparatus as recited in claim 12, wherein said load and store instructions reference segment registers in address logic which are initialized upon entry into secure execution to point to said secure volatile memory instead of said system memory.

14. The microprocessor apparatus as recited in claim 9, wherein said secure volatile memory comprises a 64-bit cache memory having 4096 locations, and wherein each of said locations comprises an internal attribute that completely isolates each of said locations.

15. The microprocessor apparatus as recited in claim 9, further comprising:

SEM logic, coupled to said secure volatile memory and to address logic in said microprocessor, configured to disable virtual address translation by said address logic when said microprocessor is executing said secure application program.

16. The microprocessor apparatus as recited in claim 15, wherein, upon execution of a secure mode enabled reset sequence by said microprocessor, said SEM logic initializes said secure volatile memory to random values.

17. A method for executing secure code within a secure execution environment, the method comprising:

providing a secure non-volatile memory for storage of the secure code;

storing the secure code within the secure non-volatile memory via private transactions accomplished over a private bus that is coupled to the secure non-volatile memory; and

fetching the secure code from the secure non-volatile memory over the private bus for execution by a microprocessor, and employing a cryptographic unit disposed within the microprocessor to decrypt the secure code using a processor unique key, wherein the processor unique key is stored in a processor key register within the microprocessor, and wherein the processor key register can only be read by the cryptographic unit, and storing the secure code in a secure volatile memory, wherein the secure volatile memory and the cryptographic unit are isolated from non-secure code and system bus resources within the microprocessor, and wherein the microprocessor is also configured to automatically transition to a degraded mode where only BIOS instructions are allowed to execute in order to allow for user input and the display of messages;

wherein the private bus is isolated from all system bus resources within the microprocessor and external to the microprocessor, and wherein the private bus is observable and accessible exclusively by secure execution logic within the microprocessor.

18. The method as recited in claim 17, wherein said storing said secure code in a secure volatile memory comprises employing the secure volatile memory as an instruction cache and a data cache.

19. The method as recited in claim 17, wherein the secure volatile memory comprises a stack for storage and retrieval of the state of the microprocessor corresponding to the non-secure code.

20. The method as recited in claim 17, wherein the secure code accesses the secure volatile memory to read and write secure data by employing load and store instructions.

21. The method as recited in claim 20, wherein the load and store instructions reference segment registers in address logic which are initialized upon entry into secure execution to point to the secure volatile memory instead of system memory.

22. The method as recited in claim 17, wherein the secure volatile memory comprises a 64-bit cache memory having 4096 locations, and wherein each of the locations comprises an internal attribute that completely isolates each of the locations.

23. The method as recited in claim 17, further comprising:

via SEM logic that is coupled to the secure volatile memory and to address logic in the microprocessor, disabling virtual address translation by the address logic when the microprocessor is executing the secure code.

24. The method as recited in claim 23, wherein, upon execution of a secure mode enabled reset sequence by the microprocessor, initializing the secure volatile memory to random values.