Re: [PATCHv2 bpf-next 4/7] libbpf: Add support for kprobe session attach

[Jiri Olsa <olsajiri@gmail.com>]

On Wed, May 01, 2024 at 11:30:55AM -0700, Andrii Nakryiko wrote:

SNIP

> >
> > +static int attach_kprobe_session(const struct bpf_program *prog, long cookie,
> > +                                struct bpf_link **link)
> > +{
> > +       LIBBPF_OPTS(bpf_kprobe_multi_opts, opts, .session = true);
> > +       const char *spec;
> > +       char *pattern;
> > +       int n;
> > +
> > +       *link = NULL;
> > +
> > +       /* no auto-attach for SEC("kprobe.session") */
> > +       if (strcmp(prog->sec_name, "kprobe.session") == 0)
> > +               return 0;
> > +
> > +       spec = prog->sec_name + sizeof("kprobe.session/") - 1;
> > +       n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
> > +       if (n < 1) {
> > +               pr_warn("kprobe session pattern is invalid: %s\n", pattern);
> 
> this should be printing spec, not pattern, please send a follow up fix, thanks

ugh yes, also attach_kprobe_multi is broken same way, will send the fix tomorrow

thanks,
jirka

> 
> > +               return -EINVAL;
> > +       }
> > +
> > +       *link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
> > +       free(pattern);
> > +       return *link ? 0 : -errno;
> > +}
> > +
> >  static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
> >  {
> >         char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
> > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> > index 1333ae20ebe6..c3f77d9260fe 100644
> > --- a/tools/lib/bpf/libbpf.h
> > +++ b/tools/lib/bpf/libbpf.h
> > @@ -539,10 +539,12 @@ struct bpf_kprobe_multi_opts {
> >         size_t cnt;
> >         /* create return kprobes */
> >         bool retprobe;
> > +       /* create session kprobes */
> > +       bool session;
> >         size_t :0;
> >  };
> >
> > -#define bpf_kprobe_multi_opts__last_field retprobe
> > +#define bpf_kprobe_multi_opts__last_field session
> >
> >  LIBBPF_API struct bpf_link *
> >  bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
> > --
> > 2.44.0
> >