From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Hao Luo <haoluo@google.com>
Cc: Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Song Liu <songliubraving@fb.com>,
Quentin Monnet <quentin@isovalent.com>
Subject: Re: [RFC PATCH bpf-next 3/8] selftests/bpf: add __ksym extern selftest
Date: Mon, 15 Jun 2020 12:11:22 -0700 [thread overview]
Message-ID: <CAEf4BzbQBNnNV2rGOJHUs1Yh2Njqu5bEtB_DsgF9AOruGorKHg@mail.gmail.com> (raw)
In-Reply-To: <CA+khW7jxdS1KRpk2syVGjDqbyn3wAd3Eh_LEMAEhkPUehuXMwg@mail.gmail.com>
On Mon, Jun 15, 2020 at 9:45 AM Hao Luo <haoluo@google.com> wrote:
>
> Andrii, a couple of general comments on fixed_percpu_data.
>
> I think it would be better to check the existence of fixed_percpu_data in kallsyms first. If it's not there, just skip, or maybe warn but not fail.
fixed_percpu_data is always there, but I missed the fact that it's
x86-specific one. I'll switch to some bpf-specific symbol (e.g., like
bpf_prog_fops or something along those lines).
>
> Further, if we really want to be sure that fixed_percpu_data is the first percpu var, we can read the value of __per_cpu_start, which marks the beginning address of the percpu section. Checking the address of fixed_percpu_data against __per_cpu_start rather than 0 should be more robust, I think, given that fixed_percpu_data exists.
There are assertions in Linux sources that fixed_percpu_data is 0, so
I don't think that it necessary. But it's a moot point, as I'll use
something less x86-specific.
>
> Hao
>
> On Fri, Jun 12, 2020 at 3:35 PM Andrii Nakryiko <andriin@fb.com> wrote:
>>
>> Validate libbpf is able to handle weak and strong kernel symbol externs in BPF
>> code correctly.
>>
>> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
>> ---
>> .../testing/selftests/bpf/prog_tests/ksyms.c | 71 +++++++++++++++++++
>> .../testing/selftests/bpf/progs/test_ksyms.c | 32 +++++++++
>> 2 files changed, 103 insertions(+)
>> create mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms.c
>> create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms.c
>>
[...]
next prev parent reply other threads:[~2020-06-15 19:11 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 22:31 [RFC PATCH bpf-next 0/8] libbpf ksym support and bpftool show PIDs Andrii Nakryiko
2020-06-12 22:31 ` [RFC PATCH bpf-next 1/8] libbpf: generalize libbpf externs support Andrii Nakryiko
[not found] ` <CA+khW7hAYVdoQX5-j0z1iGEVZeww4BBu4NXzy5eS5OwDRYqe2w@mail.gmail.com>
2020-06-15 18:55 ` Andrii Nakryiko
2020-06-12 22:31 ` [RFC PATCH bpf-next 2/8] libbpf: add support for extracting kernel symbol addresses Andrii Nakryiko
[not found] ` <CA+khW7hFZzp_K_xydSFw0O3LYB22_fC=Z4wG7i9Si+phGHn4cQ@mail.gmail.com>
2020-06-15 19:08 ` Andrii Nakryiko
2020-06-16 8:05 ` Hao Luo
2020-06-17 1:24 ` Hao Luo
2020-06-17 1:36 ` Andrii Nakryiko
2020-06-18 7:53 ` Hao Luo
2020-06-12 22:31 ` [RFC PATCH bpf-next 3/8] selftests/bpf: add __ksym extern selftest Andrii Nakryiko
[not found] ` <CA+khW7jxdS1KRpk2syVGjDqbyn3wAd3Eh_LEMAEhkPUehuXMwg@mail.gmail.com>
2020-06-15 19:11 ` Andrii Nakryiko [this message]
2020-06-12 22:31 ` [RFC PATCH bpf-next 4/8] tools/bpftool: move map/prog parsing logic into common Andrii Nakryiko
2020-06-12 22:31 ` [RFC PATCH bpf-next 5/8] tools/bpftool: minimize bootstrap bpftool Andrii Nakryiko
2020-06-12 22:31 ` [RFC PATCH bpf-next 6/8] tools/bpftool: generalize BPF skeleton support and generate vmlinux.h Andrii Nakryiko
2020-06-12 22:31 ` [RFC PATCH bpf-next 7/8] libbpf: wrap source argument of BPF_CORE_READ macro in parentheses Andrii Nakryiko
2020-06-12 22:31 ` [RFC PATCH bpf-next 8/8] tools/bpftool: show PIDs with FDs open against BPF map/prog/link/btf Andrii Nakryiko
2020-06-13 3:45 ` Alexei Starovoitov
2020-06-13 5:57 ` Andrii Nakryiko
2020-06-13 22:14 ` Arnaldo Carvalho de Melo
2020-06-15 9:04 ` Toke Høiland-Jørgensen
2020-06-15 9:30 ` Quentin Monnet
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAEf4BzbQBNnNV2rGOJHUs1Yh2Njqu5bEtB_DsgF9AOruGorKHg@mail.gmail.com \
--to=andrii.nakryiko@gmail.com \
--cc=acme@kernel.org \
--cc=andriin@fb.com \
--cc=ast@fb.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=haoluo@google.com \
--cc=kernel-team@fb.com \
--cc=netdev@vger.kernel.org \
--cc=quentin@isovalent.com \
--cc=songliubraving@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).