[LSF/MM TOPIC] BPF: Extending eBPF as a generic tracing engine

[LSF/MM TOPIC] BPF: Extending eBPF as a generic tracing engine

[Kris Van Hees]

Topic: Extending eBPF as a generic tracing engine

My presentation covers a few new features to the eBPF implementation in
support of tracing tools.  The main goal is to allow tracing tools the
ability to encode actions with probes/events, beyond the context of what
the current probes/events provide.

The features to discuss are:

    - Allowing BPF-to-BPF tail-calling between BPF programs of different
      program types (ussing a context conversion/casting mechanism that
      BPF program types can provide.  This patch is being posted to the
      netdev group this weekend, along with an example on how to use it.
    - Using the context conversion mechanism to associate task info with
      probe/event context, and have a BPF program operate on that, which
      reduces the dependency (or need) for helper functions.
    - Consider the option of having BPF program sub-types (for some program
      types), which could even provide for loadable modules to implement
      some specific extensions to a more generic BPF program type.
    - Extending the context handling code and access checking to allow
      for pointer references to auxilliary structs (to an arbitrary depth).
      This makes it possible to do a lot more with contexts, such as
      having it store a pointer to a trace output buffer so you can have
      BPF instructions store to it directly.

The talk will focus on why this will help tracing a lot, and how it will
advance BPF as a tracing facility.  I want to solicit feedback on these
features so there can be common road forward to enhancing tracing based on
BPF.

Re: [LSF/MM TOPIC] BPF: Extending eBPF as a generic tracing engine

[Kris Van Hees]

Hi,

I have not heard any reply to the topic I proosed for the BPF track?  Could
you please let me know by when notification can be expected on whether the
proposal is accepted or not?

	Cheers,
	Kris

On Fri, Feb 22, 2019 at 11:24:12PM -0500, Kris Van Hees wrote:
> Topic: Extending eBPF as a generic tracing engine
> 
> My presentation covers a few new features to the eBPF implementation in
> support of tracing tools.  The main goal is to allow tracing tools the
> ability to encode actions with probes/events, beyond the context of what
> the current probes/events provide.
> 
> The features to discuss are:
> 
>     - Allowing BPF-to-BPF tail-calling between BPF programs of different
>       program types (ussing a context conversion/casting mechanism that
>       BPF program types can provide.  This patch is being posted to the
>       netdev group this weekend, along with an example on how to use it.
>     - Using the context conversion mechanism to associate task info with
>       probe/event context, and have a BPF program operate on that, which
>       reduces the dependency (or need) for helper functions.
>     - Consider the option of having BPF program sub-types (for some program
>       types), which could even provide for loadable modules to implement
>       some specific extensions to a more generic BPF program type.
>     - Extending the context handling code and access checking to allow
>       for pointer references to auxilliary structs (to an arbitrary depth).
>       This makes it possible to do a lot more with contexts, such as
>       having it store a pointer to a trace output buffer so you can have
>       BPF instructions store to it directly.
> 
> The talk will focus on why this will help tracing a lot, and how it will
> advance BPF as a tracing facility.  I want to solicit feedback on these
> features so there can be common road forward to enhancing tracing based on
> BPF.