RE: [MI400] using _pcoptr proc. was: Attention Users of *SYSTEM State

[Don <dr2@xxxxxxxxxxxx>]

Steve,

did you ever have the opportunity to do any SPL under MPE? (HP/3000 for
the rest of you folks).  They had a bit called a priv mode which you in
effect were SYS, or root for those from eunochs land.  System state
basically lets you be god.  And if you're an evil god and you have a bug
in your program, you are a toasted god...and IBM support will say "naughty
naughty..." :)  :)

Don in DC

-----------------------------

On Thu, 10 Mar 2005, Steve Richter wrote:

> oh, it works if your program is system state.  but when IBM takes away the
> ability to make a program system state, this method will no longer work.
> Got it!
>
> Actually, I still dont understand the system state thing.  A few months ago
> I wrote a rudimentary PowerPC assembler.  I then used that assembler to
> assemble some simple PPC code and placed that code in a user space.  I then
> used SST to patch an RPG program to make it branch to my user space
> assembler code.
>
> When I was not crashing my system because of a PPC coding error I was able
> to do things like change the sub type of a user space. I was also able to
> read the bytes of a program object ( the return address in my patched RPG
> program ) and run those bytes thru a basic disassembler that I wrote.
>
> Using the 8 byte pointers of the PowerPC CPU, I set the pointer to the start
> of the object ( the 32 byte object header ).  Then I change the sub type
> field to an arbitrary value.  It made the user space disappear!   I thought
> your program had to be system state to change the sub type of an object or
> read the bytes of a program object?
>
> -Steve
>
> -----Original Message-----
> From: mi400-bounces@xxxxxxxxxxxx [mailto:mi400-bounces@xxxxxxxxxxxx]On
> Behalf Of Douglas Handy
> Sent: Thursday, March 10, 2005 1:16 PM
> To: MI Programming on the AS400 / iSeries
> Subject: Re: [MI400] using _pcoptr proc. was: Attention Users of *SYSTEM
> State
>
>
> Steve,
>
> > How does this code that Gene posted run without getting a storage
> protection
> > violation (MCH6801) ?
>
> Isn't that the point of Gene's request for a sanctioned API to do this
> instead of the unauthorized means necessary now?
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