From: Jiri Olsa <jolsa@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
Martin KaFai Lau <kafai@fb.com>, David Miller <davem@redhat.com>,
John Fastabend <john.fastabend@gmail.com>,
Wenbo Zhang <ethercflow@gmail.com>,
KP Singh <kpsingh@chromium.org>, Andrii Nakryiko <andriin@fb.com>,
Brendan Gregg <bgregg@netflix.com>,
Florent Revest <revest@chromium.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH 03/11] bpf: Add btf_ids object
Date: Fri, 19 Jun 2020 15:13:06 +0200 [thread overview]
Message-ID: <20200619131306.GD2465907@krava> (raw)
In-Reply-To: <CAEf4BzZ=BN7zDU_8xMEEoF7khjC4bwGitU+iYf+6uFXPZ_=u-g@mail.gmail.com>
On Thu, Jun 18, 2020 at 05:56:38PM -0700, Andrii Nakryiko wrote:
> On Tue, Jun 16, 2020 at 3:05 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Adding support to generate .BTF_ids section that would
> > hold various BTF IDs list for verifier.
> >
> > Adding macros help to define lists of BTF IDs placed in
> > .BTF_ids section. They are initially filled with zeros
> > (during compilation) and resolved later during the
> > linking phase by btfid tool.
> >
> > Following defines list of one BTF ID that is accessible
> > within kernel code as bpf_skb_output_btf_ids array.
> >
> > extern int bpf_skb_output_btf_ids[];
> >
> > BTF_ID_LIST(bpf_skb_output_btf_ids)
> > BTF_ID(struct, sk_buff)
> >
> > Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > include/asm-generic/vmlinux.lds.h | 4 ++
> > kernel/bpf/Makefile | 2 +-
> > kernel/bpf/btf_ids.c | 3 ++
> > kernel/bpf/btf_ids.h | 70 +++++++++++++++++++++++++++++++
> > 4 files changed, 78 insertions(+), 1 deletion(-)
> > create mode 100644 kernel/bpf/btf_ids.c
> > create mode 100644 kernel/bpf/btf_ids.h
> >
>
> [...]
>
> > +/*
> > + * Following macros help to define lists of BTF IDs placed
> > + * in .BTF_ids section. They are initially filled with zeros
> > + * (during compilation) and resolved later during the
> > + * linking phase by btfid tool.
> > + *
> > + * Any change in list layout must be reflected in btfid
> > + * tool logic.
> > + */
> > +
> > +#define SECTION ".BTF_ids"
>
> nit: SECTION is super generic and non-greppable. BTF_IDS_SECTION?
ok
>
> > +
> > +#define ____BTF_ID(symbol) \
> > +asm( \
> > +".pushsection " SECTION ",\"a\"; \n" \
>
> section should be also read-only? Either immediately here, of btfid
> tool should mark it? Unless I missed that it's already doing it :)
hm, it's there next to the .BTF section within RO_DATA macro,
so I thought that was enough.. I'll double check
>
> > +".local " #symbol " ; \n" \
> > +".type " #symbol ", @object; \n" \
> > +".size " #symbol ", 4; \n" \
> > +#symbol ": \n" \
> > +".zero 4 \n" \
> > +".popsection; \n");
> > +
> > +#define __BTF_ID(...) \
> > + ____BTF_ID(__VA_ARGS__)
>
> why varargs, if it's always a single argument? Or it's one of those
> macro black magic things were it works only in this particular case,
> but not others?
yea, I kind of struggled in here, because any other would not
expand the name concat together with the unique ID bit,
__VA_ARGS__ did it nicely ;-) I'll revisit this
thanks,
jirka
next prev parent reply other threads:[~2020-06-19 13:13 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 10:05 [PATCHv3 0/9] bpf: Add d_path helper Jiri Olsa
2020-06-16 10:05 ` [PATCH 01/11] bpf: Add btfid tool to resolve BTF IDs in ELF object Jiri Olsa
2020-06-19 0:38 ` Andrii Nakryiko
2020-06-19 13:03 ` Jiri Olsa
2020-06-19 18:12 ` Andrii Nakryiko
2020-06-22 8:59 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 02/11] bpf: Compile btfid tool at kernel compilation start Jiri Olsa
2020-06-18 20:40 ` John Fastabend
2020-06-18 21:17 ` John Fastabend
2020-06-19 13:23 ` Jiri Olsa
2020-06-19 0:40 ` Andrii Nakryiko
2020-06-19 0:47 ` Arnaldo Carvalho de Melo
2020-06-19 2:08 ` Alexei Starovoitov
2020-06-19 3:51 ` Andrii Nakryiko
2020-06-16 10:05 ` [PATCH 03/11] bpf: Add btf_ids object Jiri Olsa
2020-06-19 0:56 ` Andrii Nakryiko
2020-06-19 1:06 ` Andrii Nakryiko
2020-06-19 13:16 ` Jiri Olsa
2020-06-19 13:13 ` Jiri Olsa [this message]
2020-06-19 18:15 ` Andrii Nakryiko
2020-06-19 1:02 ` Andrii Nakryiko
2020-06-19 13:05 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 04/11] bpf: Resolve BTF IDs in vmlinux image Jiri Olsa
2020-06-16 10:05 ` [PATCH 05/11] bpf: Remove btf_id helpers resolving Jiri Olsa
2020-06-19 1:10 ` Andrii Nakryiko
2020-06-19 13:18 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 06/11] bpf: Do not pass enum bpf_access_type to btf_struct_access Jiri Olsa
2020-06-19 3:58 ` Andrii Nakryiko
2020-06-19 13:23 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 07/11] bpf: Allow nested BTF object to be refferenced by BTF object + offset Jiri Olsa
2020-06-16 10:05 ` [PATCH 08/11] bpf: Add BTF whitelist support Jiri Olsa
2020-06-19 4:29 ` Andrii Nakryiko
2020-06-19 13:29 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 09/11] bpf: Add d_path helper Jiri Olsa
2020-06-19 4:35 ` Andrii Nakryiko
2020-06-19 13:31 ` Jiri Olsa
2020-06-19 18:25 ` Andrii Nakryiko
2020-06-22 9:02 ` Jiri Olsa
2020-06-22 19:18 ` Andrii Nakryiko
2020-06-23 10:02 ` Jiri Olsa
2020-06-23 18:58 ` Andrii Nakryiko
2020-06-23 20:14 ` Jiri Olsa
2020-06-23 20:17 ` Andrii Nakryiko
2020-06-16 10:05 ` [PATCH 10/11] selftests/bpf: Add verifier test for " Jiri Olsa
2020-06-19 4:38 ` Andrii Nakryiko
2020-06-19 13:32 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 11/11] selftests/bpf: Add " Jiri Olsa
2020-06-19 4:44 ` Andrii Nakryiko
2020-06-19 13:34 ` Jiri Olsa
2020-06-18 20:57 ` [PATCHv3 0/9] bpf: Add " John Fastabend
2020-06-19 12:35 ` Jiri Olsa
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=20200619131306.GD2465907@krava \
--to=jolsa@redhat.com \
--cc=andrii.nakryiko@gmail.com \
--cc=andriin@fb.com \
--cc=ast@kernel.org \
--cc=bgregg@netflix.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@redhat.com \
--cc=ethercflow@gmail.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kafai@fb.com \
--cc=kpsingh@chromium.org \
--cc=netdev@vger.kernel.org \
--cc=revest@chromium.org \
--cc=songliubraving@fb.com \
--cc=viro@zeniv.linux.org.uk \
--cc=yhs@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).