Re: [RFC/PATCH bpf-next 08/20] libbpf: Add elf_find_patern_func_offset function

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On Thu, Apr 27, 2023 at 6:21 AM Jiri Olsa <olsajiri@xxxxxxxxx> wrote:
>
> On Wed, Apr 26, 2023 at 12:24:16PM -0700, Andrii Nakryiko wrote:
> > On Mon, Apr 24, 2023 at 9:06 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> > >
> > > Adding elf_find_patern_func_offset function that looks up
> > > offsets for symbols specified by pattern argument.
> > >
> > > The 'pattern' argument allows wildcards (*?' supported).
> > >
> > > Offsets are returned in allocated array together with its
> > > size and needs to be released by the caller.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > > ---
> >
> >
> > Why do we need to expose any elf-related helpers as libbpf public API?
> > Just to use them in selftests? If yes, then selftests can use libbpf
> > internal helpers just like bpftool due to static linking. In general,
> > it of course doesn't make sense for libbpf to provide ELF helpers as
> > part of its API.
>
> I use them in bpftrace ;-) I can move the implementation in there,
> if we don't want to expose it.. it was just convenient to use libbpf

yep, let's not expose elf helpers as libbpf UAPI

>
> >
> > Also s/patern/pattern/.
>
> ok
>
> >
> >
> > >  tools/lib/bpf/libbpf.c   | 121 +++++++++++++++++++++++++++++++++++++++
> > >  tools/lib/bpf/libbpf.h   |   7 +++
> > >  tools/lib/bpf/libbpf.map |   1 +
> > >  3 files changed, 129 insertions(+)
> > >
> > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > > index 0b15609d4573..7eb7035f7b73 100644
> > > --- a/tools/lib/bpf/libbpf.c
> > > +++ b/tools/lib/bpf/libbpf.c
> > > @@ -11052,6 +11052,127 @@ elf_find_multi_func_offset(const char *binary_path, int cnt,
> > >         return ret;
> > >  }
> > >
> > > +struct match_pattern_data {
> > > +       const char *pattern;
> > > +       struct elf_func_offset *func_offs;
> > > +       size_t func_offs_cnt;
> > > +       size_t func_offs_cap;
> > > +};
> > > +
> > > +static int pattern_done(void *_data)
> > > +{
> > > +       struct match_pattern_data *data = _data;
> > > +
> > > +       // If we found anything in the first symbol section, do not search others
> > > +       // to avoid duplicates.
> >
> > C++ comment
>
> ok, will fix
>
> thanks,
> jirka




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