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From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andrii@kernel.org>,
	"Martin KaFai Lau" <kafai@fb.com>,
	"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
	"Jesper Dangaard Brouer" <brouer@redhat.com>,
	"Toke Høiland-Jørgensen" <toke@redhat.com>,
	Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next v4 11/11] bpf: selftests: Add selftests for module kfunc support
Date: Wed, 22 Sep 2021 11:36:08 +0530	[thread overview]
Message-ID: <20210922060608.fxdaeguiako4oixb@apollo.localdomain> (raw)
In-Reply-To: <CAEf4BzaAjHNoEPFBCmPFQm_vqk_Tj0YYEF8X0ZX9RpmzeeJnhw@mail.gmail.com>

On Wed, Sep 22, 2021 at 05:33:26AM IST, Andrii Nakryiko wrote:
> > [...]
> > Hmm, good idea, I'd just need to fill in the BTF id dynamically at runtime,
> > but that should be possible.
> >
> > Though we still need to craft distinct calls (I am trying to test the limit
> > where insn->off is different for each case). Since we try to reuse index in both
> > gen_loader and libbpf, just generating same call 256 times would not be enough.
>
> You just need to generate one instruction with offset = 257 to test
> this. And separately one call with fd_array that has module BTF fd at
> fd_array[256] (to check that 256 is ok). Or am I missing something?
>

That won't be enough, if I just pass insn->imm = id, insn->off = 257, it becomes
first descriptor in kfunc_tab and kfunc_btf_tab. The total limit is 256, and
they are kept in sorted order by based on id and off for the first, off for the
second. So 256 different offs are needed (imm may be same actually), so that
both fill up.

--
Kartikeya

  reply	other threads:[~2021-09-22  6:06 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-20 14:15 [PATCH bpf-next v4 00/11] Support kernel module function calls from eBPF Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 01/11] bpf: Introduce BPF support for kernel module function calls Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 02/11] bpf: Be conservative while processing invalid kfunc calls Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 03/11] bpf: btf: Introduce helpers for dynamic BTF set registration Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 04/11] tools: Allow specifying base BTF file in resolve_btfids Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 05/11] bpf: Enable TCP congestion control kfunc from modules Kumar Kartikeya Dwivedi
2021-09-21 22:18   ` Andrii Nakryiko
2021-09-21 22:23     ` Kumar Kartikeya Dwivedi
2021-09-21 23:02       ` Andrii Nakryiko
2021-09-20 14:15 ` [PATCH bpf-next v4 06/11] libbpf: Support kernel module function calls Kumar Kartikeya Dwivedi
2021-09-21 22:41   ` Andrii Nakryiko
2021-09-24 23:54     ` Kumar Kartikeya Dwivedi
2021-09-25  0:30       ` Andrii Nakryiko
2021-09-20 14:15 ` [PATCH bpf-next v4 07/11] libbpf: Resolve invalid weak kfunc calls with imm = 0, off = 0 Kumar Kartikeya Dwivedi
2021-09-21 22:47   ` Andrii Nakryiko
2021-09-20 14:15 ` [PATCH bpf-next v4 08/11] libbpf: Update gen_loader to emit BTF_KIND_FUNC relocations Kumar Kartikeya Dwivedi
2021-09-21  0:57   ` Alexei Starovoitov
2021-09-21  4:50     ` Kumar Kartikeya Dwivedi
2021-09-21 19:04       ` Alexei Starovoitov
2021-09-21 22:25         ` Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 09/11] tools: bpftool: Add separate fd_array map support for light skeleton Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 10/11] libbpf: Fix skel_internal.h to set errno on loader retval < 0 Kumar Kartikeya Dwivedi
2021-09-20 14:15 ` [PATCH bpf-next v4 11/11] bpf: selftests: Add selftests for module kfunc support Kumar Kartikeya Dwivedi
2021-09-21 23:00   ` Andrii Nakryiko
2021-09-21 23:13     ` Kumar Kartikeya Dwivedi
2021-09-21 23:28       ` Kumar Kartikeya Dwivedi
2021-09-22  0:03       ` Andrii Nakryiko
2021-09-22  6:06         ` Kumar Kartikeya Dwivedi [this message]
2021-09-22 18:24           ` Alexei Starovoitov
2021-09-21  0:29 ` [PATCH bpf-next v4 00/11] Support kernel module function calls from eBPF Andrii Nakryiko
2021-09-21  4:55   ` Kumar Kartikeya Dwivedi

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