Re: [RFC PATCH bpf-next 1/1] libbpf: Auto-upgrade uprobes to multi-uprobes when supported

[Varun R Mallya]

On Thu, Feb 12, 2026 at 04:06:22PM -0800, Yonghong Song wrote:
>
>
> On 2/12/26 7:20 AM, Varun R Mallya wrote:
> > This patch modifies libbpf to automatically "upgrade" standard
> > SEC("uprobe") and SEC("uretprobe") programs to use the multi-uprobe
> > infrastructure (BPF_TRACE_UPROBE_MULTI) at load time if the kernel
> > supports it, making them compatible with BPF tokens.
> >
> > To maintain backward compatibility and handle rare cases where singular
> > uprobes are required, new SEC("uprobe.single") and SEC("uretprobe.single")
> > section types are introduced. These force libbpf to use the legacy
> > perf_event_open() attachment path.
>
> Maybe you can have bpf programs for both uprobe/uretprobe
> and uprobe.multi/uretprobe.multi?
>
> You can add "?" before the section name (e.g., SEC("?uprobe") so you can
> selectively enable those programs before loading. This one if one choice
> e.g. uprobe/uretprobe is not working, you can then try
> uprobe.multi/uretprobe.multi.

This is a good idea, but isn't making the upgradation built-in a better
choice ?
This way, anyone writing the program does not have to rewrite
the same thing twice, keeping their programs pretty clean. This also
moves the upgradation logic (which is probably going to be repeated multiple times)
into the library which makes it easier for anyone to have something BPF
Token compatible without having to write all this extra logic. Since "uprobe.multi"
is compatible with "uprobe", I don't think anything will break as well.
(The current breakages in the selftests are due to the patch being in
nascent stages and I'll fix it after I get some feedback on my
questions.)