On Fri, May 07, 2021 at 01:31:54AM +0200, Daniel Borkmann wrote: > On 5/5/21 8:45 PM, Andrii Nakryiko wrote: > > On Wed, May 5, 2021 at 6:42 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > > > > > We can't currently allow to attach functions with variable arguments. > > > The problem is that we should save all the registers for arguments, > > > which is probably doable, but if caller uses more than 6 arguments, > > > we need stack data, which will be wrong, because of the extra stack > > > frame we do in bpf trampoline, so we could crash. > > > > > > Also currently there's malformed trampoline code generated for such > > > functions at the moment as described in: > > > https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@xxxxxxxxxx/ > > > > > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > > > --- > > > > LGTM. > > > > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > > > > kernel/bpf/btf.c | 13 +++++++++++++ > > > 1 file changed, 13 insertions(+) > > > > > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > > > index 0600ed325fa0..161511bb3e51 100644 > > > --- a/kernel/bpf/btf.c > > > +++ b/kernel/bpf/btf.c > > > @@ -5206,6 +5206,13 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, > > > m->ret_size = ret; > > > > > > for (i = 0; i < nargs; i++) { > > > + if (i == nargs - 1 && args[i].type == 0) { > > > + bpf_log(log, > > > + "The function %s with variable args is unsupported.\n", > > > + tname); > > > + return -EINVAL; > > > + > > (Jiri, fyi, I removed this extra newline while applying. Please scan for such > things before submitting.) sorry, will do jirka
