On Thu, 15 Jul 2010 20:03:26 +1000 robin <[email protected]> wrote:
:>From: Binyamin Dissen <[email protected]> :>Date: Thursday, 15 July 2010 16:50 :>>On Thu, 15 Jul 2010 11:25:06 +1000 robin <[email protected]> wrote: :>>:>It's possible in the s/390 architecture to trap (inhibit) non-priveleged :>>:>instructions, using EX to execute every instruction [except, of course, :>>:>EX itself]. The overheads are not "an order of magnitude", but are :>>:>not trivial either. :>>:>We did this [use EX to execute programs] in a load-and-go assembler :>>:>that provided run-time diagnostic support. :>>And branch instructions. :>What do you mean? :>A branch instruction is EXecuted just like the others. :>The only difference is that the branch address needs checking prior to execution. After a branch, you do not continue at the instruction after the EX. This simply EXing each instruction does not allow single stepping. :>>An the choice of the base register to use to point to the instruction. The :>>instruction would have to be interpreted :>No it doesn't, and I didn't. :>The instructions were executed, in place, with EX. What does that mean? What happens when a relocated relative instruction is EXed? Say the instruction is LARL R3,ADDR To EX it you need to know that you cannot use R3. TRT 28(8,R4),132(R5) To EX it you need to know that R4, R$, R2 & R1 are in use. Etc. :>> to determine what register is available. -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies.
