From: Maciej Fijalkowski <maciejromanfijalkowski@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
ast@kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org,
bjorn.topel@intel.com, magnus.karlsson@intel.com
Subject: Re: [PATCH bpf-next 3/5] bpf: propagate poke descriptors to subprograms
Date: Fri, 17 Jul 2020 11:36:49 +0200 [thread overview]
Message-ID: <CAOuyyO4UWe7+=0bunQgv=yMOsLvC6PmnW6cgzorj19fWY0kgrg@mail.gmail.com> (raw)
In-Reply-To: <93a9ff59-79d1-34ac-213e-1586fd0d04ef@iogearbox.net>
On Thu, Jul 16, 2020 at 11:18 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
>
> On 7/16/20 1:36 AM, Maciej Fijalkowski wrote:
> > Previously, there was no need for poke descriptors being present in
> > subprogram's bpf_prog_aux struct since tailcalls were simply not allowed
> > in them. Each subprog is JITed independently so in order to enable
> > JITing such subprograms, simply copy poke descriptors from main program
> > to subprogram's poke tab.
> >
> > Add also subprog's aux struct to the BPF map poke_progs list by calling
> > on it map_poke_track().
> >
> > Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> > ---
> > kernel/bpf/verifier.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index 6481342b31ba..3b406b2860ef 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -9932,6 +9932,9 @@ static int jit_subprogs(struct bpf_verifier_env *env)
> > goto out_undo_insn;
> >
> > for (i = 0; i < env->subprog_cnt; i++) {
> > + struct bpf_map *map_ptr;
> > + int j;
> > +
> > subprog_start = subprog_end;
> > subprog_end = env->subprog_info[i + 1].start;
> >
> > @@ -9956,6 +9959,12 @@ static int jit_subprogs(struct bpf_verifier_env *env)
> > func[i]->aux->btf = prog->aux->btf;
> > func[i]->aux->func_info = prog->aux->func_info;
> >
> > + for (j = 0; j < prog->aux->size_poke_tab; j++) {
> > + bpf_jit_add_poke_descriptor(func[i], &prog->aux->poke_tab[j]);
> > + map_ptr = func[i]->aux->poke_tab[j].tail_call.map;
> > + map_ptr->ops->map_poke_track(map_ptr, func[i]->aux);
>
> Error checking missing for bpf_jit_add_poke_descriptor() and map_poke_track() ..? It
> must be guaranteed that adding this to the tracker must not fail, otherwise this will
> be a real pain to debug given the prog will never be patched.
My bad, will fix it in v2.
>
> > + }
> > +
> > /* Use bpf_prog_F_tag to indicate functions in stack traces.
> > * Long term would need debug info to populate names
> > */
> >
>
next prev parent reply other threads:[~2020-07-17 9:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 23:36 [PATCH bpf-next 0/5] bpf: tailcalls in BPF subprograms Maciej Fijalkowski
2020-07-15 23:36 ` [PATCH bpf-next 1/5] bpf, x64: use %rcx instead of %rax for tail call retpolines Maciej Fijalkowski
2020-07-16 20:36 ` Daniel Borkmann
2020-07-17 9:29 ` Maciej Fijalkowski
2020-07-15 23:36 ` [PATCH bpf-next 2/5] bpf: allow for tailcalls in BPF subprograms Maciej Fijalkowski
2020-07-16 21:10 ` Daniel Borkmann
2020-07-16 21:29 ` Daniel Borkmann
2020-07-16 22:46 ` Daniel Borkmann
2020-07-17 11:39 ` Maciej Fijalkowski
2020-07-15 23:36 ` [PATCH bpf-next 3/5] bpf: propagate poke descriptors to subprograms Maciej Fijalkowski
2020-07-16 21:16 ` Daniel Borkmann
2020-07-17 9:36 ` Maciej Fijalkowski [this message]
2020-07-15 23:36 ` [PATCH bpf-next 4/5] bpf, x64: rework pro/epilogue and tailcall handling in JIT Maciej Fijalkowski
2020-07-16 23:06 ` Daniel Borkmann
2020-07-17 2:16 ` Alexei Starovoitov
2020-07-17 10:57 ` Maciej Fijalkowski
2020-07-17 16:16 ` Alexei Starovoitov
2020-07-17 10:52 ` Maciej Fijalkowski
2020-07-15 23:36 ` [PATCH bpf-next 5/5] selftests: bpf: add dummy prog for bpf2bpf with tailcall Maciej Fijalkowski
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