/*************************************************************************************************/ x = cfun->machine->force_align_arg_pointer; x = gen_frame_mem (Pmode, plus_constant (x, -8)) xor hard_frame_pointer_rtx; insn = emit_insn (gen_push (x)); RTX_FRAME_RELATED_P (insn) = 1; /*************************************************************************************************/
I am trying to push a copy of return address just below the return address and xor it with the "frame pointer". I wanted to know if the above code is correct for pushing the return address and encrypt it with the frame pointer. Now, in the epilogue I want to decrypt this copy of return address with the pushed frame pointer and verify if the two instances (original and decrypted) of the return address are same. This is the first time I am working on an approach that requires to make modifications to the ix86_expand_prologue/epilogue methods of the compiler. I also wanted to know how to read the value of encrypted return address in the ix86_expand_epilogue method, since then I need to decrypt it and compare it with the original return address pushed on the stack. -- Vaibhav Shrimali BTech(ICT), DA-IICT Gandhinagar, INDIA
