Re: [PATCH v13 02/14] unwind_user: Add frame pointer support

On Thu, 10 Jul 2025 17:41:36 +0200
Jens Remus [off-list ref] wrote:

cfa + frame->ra_off could be aligned by chance.  So could
cfa + frame->fp_off be as well of course.

On s390 the CFA must be aligned (as the SP must be aligned) and the
FP and RA offsets from CFA must be aligned, as pointer / 64-bit integers
(such as 64-bit register values) must be aligned as well.

So the CFA (and/or offset), FP offset, and RA offset could be validated
individually.  Not sure if that would be over engineering though.

I wonder if we should just validate that cfa is aligned? Would that work?

I would think that ra_off and fp_off should be aligned as well and if
cfa is aligned then it would still be aligned when adding those offsets.

-- Steve