Re: [patch part-II V2 01/13] context_tracking: Ensure that the critical path cannot be instrumented

[Frederic Weisbecker]

On Sun, Mar 08, 2020 at 11:24:00PM +0100, Thomas Gleixner wrote:
> context tracking lacks a few protection mechanisms against instrumentation:
> 
>  - While the core functions are marked NOKPROBE they lack protection
>    against function tracing which is required as the function entry/exit
>    points can be utilized by BPF.

Just to clarify things up: IIUC, BPF scripts can be called from the
function graph tracer hooks, and that BPF code uses RCU, right?

> 
>  - static functions invoked from the protected functions need to be marked
>    as well as they can be instrumented otherwise.
> 
>  - using plain inline allows the compiler to emit traceable and probable
>    functions.
> 
> Fix this by adding the missing notrace/NOKPROBE annotations and converting
> the plain inlines to __always_inline.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Acked-by: Frederic Weisbecker <frederic@xxxxxxxxxx>