Patent ID: 8645704
Filing Date: 2014-02-04
Classification: G06F

Abstract:
1. A method for restricting access of a first code of a plurality of codes of a first function from a second function, the method comprising: calling the second function by the first function, wherein addresses of the plurality of codes of the first function are stored in a stack page in a memory device and colored in a first color; passing control of an order of execution of instructions of the first and second functions to a transition page in a memory device, the transition page configured to receive a call from the first function to the second function and to set a Parallel Page Table Entry (PPTE), the PPTE having a first and at least a second field associated with the first function and the second function, respectively, the first and second field having a first and a second number of bits, respectively, configured to represent colors; performing access control check via the transition page for verifying whether the first function has permission to call the second function; protecting the first code of the first function from the second function via the transition page by setting the first number of bits of the first field of the PPTE to a second color; executing the second function by pushing addresses of the second function on the stack page, the addresses of the second function colored in a third color by setting the second number of bits in the second field via the transition page to represent the third color; and unprotecting the first code of the first function via the transition page by setting the first number of bits of the first field of the PPTE to the first color; wherein the addresses of the plurality of codes are colored in the first color, the second color and the third color by using bit patterns in the stack page.