Turning off the high order bit? UMH. Sounds like an AND X"7F" against that byte. It might think it is an address in the parameter list (R1) but it actually has the entry point of the program (R15).
On Fri, Feb 21, 2014 at 5:58 PM, Tony Harminc <[email protected]> wrote: > On 21 February 2014 11:37, Chase, John <[email protected]> wrote: >> Browsing the dumped storage around the program's load address (x'00007000') >> I see: >> >> Event 1 CSECT DBR915B0 GPR 15 (Address 00007000) >> 00007000 80ECD00C *..}. * >> --------------------^^^^^^^^ >> >> WTF??? >> >> In the program source the first instruction is: >> >> USING *,R15 >> DBR915B0 CSECT >> STM R14,R12,12(R13) >> >> But STM's opcode is x'90', not x'80'. X'80' is SSM (Set System Mask), which >> is a(nother) privileged instruction. > > And one that the program could not have survived executing; it is not > only privileged, but in most cases you will encounter on z/OS will > produce a special operation exception if your program *is* in > supervisor state. > > So, assuming this is the entry point of the program, that is, the > first instruction to be executed and not only the first one physically > in the module, it seems very likely that this instruction was modified > after some part of the program had already executed. > >> So, it appears that for some as-yet undetermined reason, this program (to >> the exclusion of all others) IFF loaded from a PDSE has its first >> instruction changed somehow from STM to SSM. Can you say "That's absurd!"? > > That's absurd!. But I can also say as above that it's unlikely it was > loaded that way. > > Tony H. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
