From: Daniel Borkmann <daniel@iogearbox.net>
To: Maciej Fijalkowski <maciej.fijalkowski@intel.com>, ast@kernel.org
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org,
bjorn.topel@intel.com, magnus.karlsson@intel.com
Subject: Re: [PATCH bpf-next 2/5] bpf: allow for tailcalls in BPF subprograms
Date: Thu, 16 Jul 2020 23:29:28 +0200 [thread overview]
Message-ID: <912b5e97-1951-5a7c-e3c1-41bc3bf4b58a@iogearbox.net> (raw)
In-Reply-To: <20200715233634.3868-3-maciej.fijalkowski@intel.com>
On 7/16/20 1:36 AM, Maciej Fijalkowski wrote:
> Relax verifier's restriction that was meant to forbid tailcall usage
> when subprog count was higher than 1.
>
> Also, do not max out the stack depth of program that utilizes tailcalls.
>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> ---
> kernel/bpf/verifier.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 3c1efc9d08fd..6481342b31ba 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -4172,10 +4172,6 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> case BPF_FUNC_tail_call:
> if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
> goto error;
> - if (env->subprog_cnt > 1) {
> - verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
> - return -EINVAL;
> - }
> break;
> case BPF_FUNC_perf_event_read:
> case BPF_FUNC_perf_event_output:
> @@ -10252,7 +10248,6 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
> * the program array.
> */
> prog->cb_access = 1;
> - env->prog->aux->stack_depth = MAX_BPF_STACK;
> env->prog->aux->max_pkt_offset = MAX_PACKET_OFF;
>
> /* mark bpf_tail_call as different opcode to avoid
Also, isn't this broken when JIT is not used (as in stack oob access)?
next prev parent reply other threads:[~2020-07-16 21:29 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 [this message]
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
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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