On Thu, 28 Apr 2011 13:45:12 -0400 Peter Relson <[email protected]> wrote:
:>>>A key question is: once the SVC Screening routine has gotten control, :>how :>>>does it then make sure that the "real" SVC routine gets control both in :>>>the right environment (locks included) and also with all the right data :>>>(potentially all 16 64-bit GRs and ARs at the time of the SVC issuance, :>>>with the PSW of the issuer)? :>>Why would that be required? :>Because that is what the callee expects. As with any interface (and :>particularly one that involves a state change), if you violate the :>interface defined by the callee you may cause functional problems or :>create system integrity problems. The overriding requirement of anything :>that puts itself in the middle is to do no harm. Most SVC's document which registers contain data to be used by the SVC routine. Why would reissuing GETMAIN require the original callers R6? Only R15-R1 are part of the API. Of course, if one reissues the SVC (and it CAN be done), one must be sure to issue it in the same state and key. :>As to your point about CICS "stealing" GETMAIN (my term), it would have :>to, at least, be able to differentiate GETMAINs done by its application :>from those done within the system that just happened to be under the same :>task. That in general is difficult at best to get 100% right. In the case of CICS there is(was?) an indication in the TCA/CSA that stated whether a system or user process was running. Worst case check the address of the caller. -- 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. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
