Re: [PATCH bpf-next] selftests/bpf: more precise cpu_mitigations state detection

[Eduard Zingerman <eddyz87@gmail.com>]

On Wed, 2025-06-11 at 10:54 +0800, Yafang Shao wrote:

[...]

> > +       config = gzopen("/proc/config.gz", "rb");
> 
> The /proc/config.gz file is not enabled in certain kernel releases.
> Should we also check "/boot/config-$(uname -r)" as an alternative?
>

Oh, my... It's a zoo, on Fedora the config location is:

  /usr/lib/modules/$(uname -r)/config

Tbh, I was fixing a problem with tests execution in a specific
environment. Adding a list of common locations for config is an
option.

Another option I tried but discarded is [1], where
kernel/cpu.c:cpu_mitigations variable is read directly by a BPF
program. But this is probably too heavy-handed.

[1]  https://github.com/eddyz87/bpf/tree/better-unpriv-disabled-detector

[...]