HWE kernels should support eBPF CO-RE

[Rafael David Tinoco]

I had recent discussion with kernel team regarding support or not BTF in HWE kernels (Bionic and Focal). Having CONFIG_DEBUG_INFO_BTF option enabled for HWE kernels (v4.4 and v.4.8) would allow eBPF based code (powered by libbpf or not) to be RO.CE (https://github.com/rafaeldtinoco/portablebpf for more information).

By allowing runtime relocations, using provided BTF, libbpf binaries might end up running, without modifications, in different kernel versions (from Bionic HWE v5.4 kernel to Hirsute v5.11).

A good example would be to support tools such as:
https://github.com/aquasecurity/tracee/discussions/713#discussioncomment-665641
An ebpf powered backend for a containers security solution.

Considering:

$ rmadisonb dwarves
 dwarves | 1.9-1 | precise/universe | amd64
 dwarves | 1.10-2 | trusty | amd64
 dwarves | 1.10-2.1 | xenial/universe | amd64
 dwarves | 1.10-2.1build1 | bionic/universe | amd64
 dwarves | 1.15-2 | focal/universe | amd64
 dwarves | 1.17-1 | groovy/universe | amd64
 dwarves | 1.20-1 | hirsute/universe | amd64
 dwarves | 1.20-1 | impish/universe | amd64

And the fact that the 'pahole' binary, from dwarves package, is the one to blame, not to have CONFIG_DEBUG_INFO_BTF available, for this bug to be solved we would have to provide a backport of dwarves (at least 1.17-1) to Bionic and Focal. It could have another name (not to mess with original dwarves package and its dependencies) and it is unclear if it needs to be in [main] or [universe].

Question: Would have dwarves backported in -backports be enough for Bionic and Focal HWE kernels compilation to have CONFIG_DEBUG_INFO_BTF enabled ?

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1926330

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Dimitri John Ledkov (xnox)]

And for v5.13 kernels even newer dwarves-dfsg is needed.

[Rafael David Tinoco (rafaeldtinoco)]

I have placed a MIR for "pahole-btf" package (a backport of Impish's dwarves-dfsg package to Bionic and Focal) at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1949286. This way, the kernel builds may depend on "pahole-btf" binary package, from main, and finally include BTF debug information into Bionic and Focal HWE kernels.

[Dimitri John Ledkov (xnox)]

Note that dwarves-dfsg portion of this request was done a while back in https://bugs.launchpad.net/ubuntu/+source/dwarves-dfsg/+bug/1912811