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

[Andy Lutomirski]

> On Feb 26, 2020, at 10:59 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> ïOn 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

Can we set a percpu variable saying âin some stupid context, donât traceâ?