Re: [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check()

Peter Zijlstra
2020-02-26T19:00:07Z

On Wed, Feb 26, 2020 at 07:42:37PM +0100, Borislav Petkov wrote:
> On Wed, Feb 26, 2020 at 09:28:51AM -0800, Andy Lutomirski wrote:
> > > It entirely depends on what the goal is :-/ On the one hand I see why
> > > people might want function tracing / kprobes enabled, OTOH it's all
> > > mighty frigging scary. Any tracing/probing/whatever on an MCE has the
> > > potential to make a bad situation worse -- not unlike the same on #DF.
>
> FWIW, I had this at the beginning of the #MC handler in a feeble attempt
> to poke at this:
>
> + hw_breakpoint_disable();
> + static_key_disable(&__tracepoint_read_msr.key);
> + tracing_off();

You can't do static_key_disable() from an IST