Nicholas Piggin wrote:
On Fri Oct 21, 2022 at 3:29 AM AEST, Naveen N. Rao wrote:
Ensure a more consistent pt_regs across kprobes, optprobes and
KPROBES_ON_FTRACE:
- Drop setting trap to 0x700 under optprobes. This is not accurate and
is unnecessary. Instead, zero it out for both optprobes and
KPROBES_ON_FTRACE.
Okay I think.
- Save irq soft mask in the ftrace handler, similar to what we do in
optprobes and trap-based kprobes.
This advertises the irqs status of regs correctly, whereas previously
it was uninitialised.
- Drop setting orig_gpr3 and result to zero in optprobes. These are not
relevant under kprobes and should not be used by the handlers.
This is for CFAR, which we can't get anyway because we just branched
here. I would rather zero it explicitly though.
Is there a strong reason to zero those out?
The reason I dropped zero'ing of orig_gpr3 and result is to make
optprobes consistent with KPROBES_ON_FTRACE. If we want to retain
zero'ing orig_gpr3/result for optprobes, I think we should then go ahead
and zero those out in ftrace_regs_caller too.
Thanks,
Naveen
