From: Yonghong Song <yhs@fb.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
<netdev@vger.kernel.org>, <bpf@vger.kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>, Daniel Xu <dxu@dxuuu.xyz>,
Viktor Malik <vmalik@redhat.com>
Subject: Re: [PATCH 11/19] bpf: Add support to load multi func tracing program
Date: Mon, 7 Jun 2021 12:35:10 -0700 [thread overview]
Message-ID: <72b9258d-9a1f-2dab-ec59-f8a8a60d7653@fb.com> (raw)
In-Reply-To: <YL5jCPZhmMxfFy26@krava>
On 6/7/21 11:18 AM, Jiri Olsa wrote:
> On Sun, Jun 06, 2021 at 08:56:47PM -0700, Yonghong Song wrote:
>>
>>
>> On 6/5/21 4:10 AM, Jiri Olsa wrote:
>>> Adding support to load tracing program with new BPF_F_MULTI_FUNC flag,
>>> that allows the program to be loaded without specific function to be
>>> attached to.
>>>
>>> The verifier assumes the program is using all (6) available arguments
>>
>> Is this a verifier failure or it is due to the check in the
>> beginning of function arch_prepare_bpf_trampoline()?
>>
>> /* x86-64 supports up to 6 arguments. 7+ can be added in the future
>> */
>> if (nr_args > 6)
>> return -ENOTSUPP;
>
> yes, that's the limit.. it allows the traced program to
> touch 6 arguments, because it's the maximum for JIT
>
>>
>> If it is indeed due to arch_prepare_bpf_trampoline() maybe we
>> can improve it instead of specially processing the first argument
>> "ip" in quite some places?
>
> do you mean to teach JIT to process more than 6 arguments?
Yes. Not sure how hard it is. If it is doable with reasonable
complexity, I think it will be worth it as it will benefit this
case to avoid special tweaks of the first argument, but also
benefit other cases e.g., attaching to a kernel function with
7 or more arguments.
>
>>
>>> as unsigned long values. We can't add extra ip argument at this time,
>>> because JIT on x86 would fail to process this function. Instead we
>>> allow to access extra first 'ip' argument in btf_ctx_access.
>>>
>>> Such program will be allowed to be attached to multiple functions
>>> in following patches.
>>>
>>> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>>> ---
>>> include/linux/bpf.h | 1 +
>>> include/uapi/linux/bpf.h | 7 +++++++
>>> kernel/bpf/btf.c | 5 +++++
>>> kernel/bpf/syscall.c | 35 +++++++++++++++++++++++++++++-----
>>> kernel/bpf/verifier.c | 3 ++-
>>> tools/include/uapi/linux/bpf.h | 7 +++++++
>>> 6 files changed, 52 insertions(+), 6 deletions(-)
>>>
[...]
next prev parent reply other threads:[~2021-06-07 19:35 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-05 11:10 [RFCv3 00/19] x86/ftrace/bpf: Add batch support for direct/tracing attach Jiri Olsa
2021-06-05 11:10 ` [PATCH 01/19] x86/ftrace: Remove extra orig rax move Jiri Olsa
2021-06-05 11:10 ` [PATCH 02/19] x86/ftrace: Remove fault protection code in prepare_ftrace_return Jiri Olsa
2021-06-05 11:10 ` [PATCH 03/19] x86/ftrace: Make function graph use ftrace directly Jiri Olsa
2021-06-08 18:35 ` Andrii Nakryiko
2021-06-08 18:51 ` Jiri Olsa
2021-06-08 19:11 ` Steven Rostedt
2021-06-05 11:10 ` [PATCH 04/19] tracing: Add trampoline/graph selftest Jiri Olsa
2021-06-05 11:10 ` [PATCH 05/19] ftrace: Add ftrace_add_rec_direct function Jiri Olsa
2021-06-05 11:10 ` [PATCH 06/19] ftrace: Add multi direct register/unregister interface Jiri Olsa
2021-06-05 11:10 ` [PATCH 07/19] ftrace: Add multi direct modify interface Jiri Olsa
2021-06-05 11:10 ` [PATCH 08/19] ftrace/samples: Add multi direct interface test module Jiri Olsa
2021-06-05 11:10 ` [PATCH 09/19] bpf, x64: Allow to use caller address from stack Jiri Olsa
2021-06-07 3:07 ` Yonghong Song
2021-06-07 18:13 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 10/19] bpf: Allow to store caller's ip as argument Jiri Olsa
2021-06-07 3:21 ` Yonghong Song
2021-06-07 18:15 ` Jiri Olsa
2021-06-08 18:49 ` Andrii Nakryiko
2021-06-08 20:58 ` Jiri Olsa
2021-06-08 21:02 ` Andrii Nakryiko
2021-06-08 21:11 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 11/19] bpf: Add support to load multi func tracing program Jiri Olsa
2021-06-07 3:56 ` Yonghong Song
2021-06-07 18:18 ` Jiri Olsa
2021-06-07 19:35 ` Yonghong Song [this message]
2021-06-05 11:10 ` [PATCH 12/19] bpf: Add bpf_trampoline_alloc function Jiri Olsa
2021-06-05 11:10 ` [PATCH 13/19] bpf: Add support to link multi func tracing program Jiri Olsa
2021-06-07 5:36 ` Yonghong Song
2021-06-07 18:25 ` Jiri Olsa
2021-06-07 19:39 ` Yonghong Song
2021-06-08 15:42 ` Alexei Starovoitov
2021-06-08 18:17 ` Jiri Olsa
2021-06-08 18:49 ` Alexei Starovoitov
2021-06-08 21:07 ` Jiri Olsa
2021-06-08 23:05 ` Alexei Starovoitov
2021-06-09 5:08 ` Andrii Nakryiko
2021-06-09 13:42 ` Jiri Olsa
2021-06-09 13:33 ` Jiri Olsa
2021-06-09 5:18 ` Andrii Nakryiko
2021-06-09 13:53 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 14/19] libbpf: Add btf__find_by_pattern_kind function Jiri Olsa
2021-06-09 5:29 ` Andrii Nakryiko
2021-06-09 13:59 ` Jiri Olsa
2021-06-09 14:19 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 15/19] libbpf: Add support to link multi func tracing program Jiri Olsa
2021-06-07 5:49 ` Yonghong Song
2021-06-07 18:28 ` Jiri Olsa
2021-06-07 19:42 ` Yonghong Song
2021-06-07 20:11 ` Jiri Olsa
2021-06-09 5:34 ` Andrii Nakryiko
2021-06-09 14:17 ` Jiri Olsa
2021-06-10 17:05 ` Andrii Nakryiko
2021-06-10 20:35 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 16/19] selftests/bpf: Add fentry multi func test Jiri Olsa
2021-06-07 6:06 ` Yonghong Song
2021-06-07 18:42 ` Jiri Olsa
2021-06-09 5:40 ` Andrii Nakryiko
2021-06-09 14:29 ` Jiri Olsa
2021-06-10 17:00 ` Andrii Nakryiko
2021-06-10 20:28 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 17/19] selftests/bpf: Add fexit " Jiri Olsa
2021-06-05 11:10 ` [PATCH 18/19] selftests/bpf: Add fentry/fexit " Jiri Olsa
2021-06-09 5:41 ` Andrii Nakryiko
2021-06-09 14:29 ` Jiri Olsa
2021-06-05 11:10 ` [PATCH 19/19] selftests/bpf: Temporary fix for fentry_fexit_multi_test Jiri Olsa
2021-06-17 20:29 ` [RFCv3 00/19] x86/ftrace/bpf: Add batch support for direct/tracing attach Andrii Nakryiko
2021-06-19 8:33 ` Jiri Olsa
2021-06-19 16:19 ` Yonghong Song
2021-06-19 17:09 ` Jiri Olsa
2021-06-20 16:56 ` Yonghong Song
2021-06-20 17:47 ` Alexei Starovoitov
2021-06-21 6:46 ` Andrii Nakryiko
2021-06-21 6:50 ` Andrii Nakryiko
2021-07-06 20:26 ` Andrii Nakryiko
2021-07-07 15:19 ` 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=72b9258d-9a1f-2dab-ec59-f8a8a60d7653@fb.com \
--to=yhs@fb.com \
--cc=andriin@fb.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=dxu@dxuuu.xyz \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=jolsa@redhat.com \
--cc=kafai@fb.com \
--cc=kpsingh@chromium.org \
--cc=netdev@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=songliubraving@fb.com \
--cc=vmalik@redhat.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).