On Thu, 2023-03-30 at 16:50 +1100, Benjamin Gray wrote: > The DEXCR register is of interest when ptracing processes. Currently > it > is static, but eventually will be dynamically controllable by a > process. > If a process can control its own, then it is useful for it to be > ptrace-able to (e.g., for checkpoint-restore functionality). > > It is also relevant to core dumps (the NPHIE aspect in particular), > which use the ptrace mechanism (or is it the other way around?) to > decide what to dump. The HDEXCR is useful here too, as the NPHIE > aspect > may be set in the HDEXCR without being set in the DEXCR. Although the > HDEXCR is per-cpu and we don't track it in the task struct (it's > useless > in normal operation), it would be difficult to imagine why a > hypervisor > would set it to different values within a guest. A hypervisor cannot > safely set NPHIE differently at least, as that would break programs. > > Expose a read-only view of the userspace DEXCR and HDEXCR to ptrace. > The HDEXCR is always readonly, and is useful for diagnosing the core > dumps (as the HDEXCR may set NPHIE without the DEXCR setting it). > > Signed-off-by: Benjamin Gray <bg...@linux.ibm.com> >
I don't know much about ptrace but this looks sane. Reviewed-by: Russell Currey <rus...@russell.cc>
