PowerPC programming on as400. was: Analyzing SAV save files from a PC -- MI400

ok, it is doable to compile PowerPC assembler code on a PC into binary form.
The next step is to place that binary code in a user space on the 400.
Done.  The 400 can also be run at security level 10.  That allows patched
programs that have not been ok'd by the trusted compiler to still run on the
system, right?

Now comes the part that might cause IBM to have any offending parties
deported or banished from the planet.  I know the PowerPC jump instruction
can jump execution to any virtual address on the system.  Correct?  That
means, thanks to the single level store design of the 400, a space pointer
can be set to the location of the PowerPC binary code stored in the user
space.  To jump to that code would require two PPC instructions:  transform
the space pointer to an instruction pointer.  Jump to the instruction
pointer address.

Do the PPC instructions exist to do this?:
  - create an instruction pointer that points to a location in a user space
  - far jump to an instruction pointer address

If so, is doing this on a security 10 system a simple matter of using SST to
patch those series of instructions into an existing AS400 program?

-Steve

-----Original Message-----
From: mi400-bounces+srichter=autocoder.com@xxxxxxxxxxxx
[mailto:mi400-bounces+srichter=autocoder.com@xxxxxxxxxxxx]On Behalf Of
Dave McKenzie
Sent: Thursday, August 26, 2004 1:47 PM
To: MI Programming on the AS400 / iSeries
Subject: RE: [MI400] Analyzing SAV save files from a PC


iSeries doesn't have a PowerPC assembler, per se.  The compilers
generate object-level W-code, which is then translated into NMI (New MI)
and then into PowerPC machine code.  No human-readable source code is
involved.



However, there are free PowerPC assemblers in the wild.  The GCC C/C++
compiler generates assembler source, which is then compiled by the GNU
assembler, "as".  It supports PowerPC, such as used by OS X on Power
Macs, including the 64-bit G5's.

Since source code for "as" is available, you could adapt it to iSeries
by adding the few iSeries-specific PowerPC machine instructions.

Let us know when you have the beta ready.  I'm sure we'll all be glad to
test it :-)

--Dave


On Thu, 2004-08-26 at 09:45, Steve Richter wrote:
> Dave,
>
> this is great stuff.  For your next assignment please unlock the PowerPC
> assembler that must lie at the core of the iSeries!  It would make my day
if
> I write PPC assembler code that sets an instruction pointer to code in a
> user space and then executes a far jump to that code.
>
> -Steve


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