The only thing I see 16 bytes in the PSA is PSAPCPSW
Sent from my iPhone
On Dec 1, 2010, at 11:25 AM, Tony Harminc <[email protected]> wrote:
On 1 December 2010 10:46, Edward Jaffe <[email protected]>
wrote:
You can use an ordinary branch instruction (e.g., BASSM 14,15) to
branch to
code above the bar. If you're running enabled, you won't execute
for long... :-D
Just how does it fail? Is the PSW instruction address silently
truncated upon return from an interrupt as a result of its having been
saved in a legacy control block, leading to continued execution at a
presumably incorrect address, or is there some active detection and
abend? Something else? What if I install the same code at, say
00000000_00123000 and 00000070_00123000, and branch to the
above-the-bar code?
Yes, I''m sure I could try it, and perhaps there even exists enough
non-secret knowledge outside IBM to research it, but since I can't
think of a real use for it I'll leave it as a Gedankenexperiment .
It is, though, curious that there must be, as Paul Gilmartin points
out, quite a bit of infrastructure already there in support of 64-bit
addresses. The real PSW is at all times beyond the early stage of IPL
a zArch one of 128 bits, and it must be saved and restored properly,
as must things like PER addresses in control registers. What remains
to be done?
Tony H.
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