Re: [RFC 0/5] mm/bpf/perf: Store build id in file object

Alexei Starovoitov
2023-02-02T11:16:08Z

On Wed, Feb 1, 2023 at 5:57 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> hi,
> we have a use cases for bpf programs to use binary file's build id.
>
> After some attempts to add helpers/kfuncs [1] [2] Andrii had an idea [3]
> to store build id directly in the file object. That would solve our use
> case and might be beneficial for other profiling/tracing use cases with
> bpf programs.
>
> This RFC patchset adds new config CONFIG_FILE_BUILD_ID option, which adds
> build id object pointer to the file object when enabled. The build id is
> read/populated when the file is mmap-ed.
>
> I also added bpf and perf changes that would benefit from this.
>
> I'm not sure what's the policy on adding stuff to file object, so apologies
> if that's out of line. I'm open to any feedback or suggestions if there's
> better place or way to do this.

struct file represents all files while build_id is for executables only,
and not all executables, but those currently running, so
I think it's cleaner to put it into vm_area_struct.