From: Alexei Starovoitov <ast@plumgrid.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Namhyung Kim <namhyung@kernel.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Jiri Olsa <jolsa@redhat.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
"David S. Miller" <davem@davemloft.net>,
Linux API <linux-api@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: [PATCH v4 tip 3/7] tracing: allow BPF programs to call ktime_get_ns()
Date: Sat, 28 Feb 2015 09:21:20 -0800 [thread overview]
Message-ID: <CAMEtUux5qv=b8HM1_p_WV5_HWzgmJhSq+AHSGQ4Ag9c-QLr81A@mail.gmail.com> (raw)
On Sat, Feb 28, 2015 at 2:20 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>>
>> +static u64 bpf_ktime_get_ns(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
>> +{
>> + return ktime_get_ns();
>> +}
>
> Please use ktime_get_mono_fast_ns() instead. If you ever want to allow
> running BPF stuff from general tracepoints and the like you need to
> be NMI safe.
good point. will do.
Currently in trace_call_bpf() I have:
if (in_nmi()) /* not supported yet */
return 1;
to tackle nmi after all pieces are in place.
Likely nmi-safe programs will have access to reduced set
of helper functions.
next reply other threads:[~2015-02-28 17:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-28 17:21 Alexei Starovoitov [this message]
-- strict thread matches above, loose matches on Subject: below --
2015-02-28 0:08 [PATCH v4 tip 0/7] tracing: attach eBPF programs to kprobes Alexei Starovoitov
[not found] ` <1425082135-11967-1-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-02-28 0:08 ` [PATCH v4 tip 3/7] tracing: allow BPF programs to call ktime_get_ns() Alexei Starovoitov
[not found] ` <1425082135-11967-4-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-02-28 10:20 ` Peter Zijlstra
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='CAMEtUux5qv=b8HM1_p_WV5_HWzgmJhSq+AHSGQ4Ag9c-QLr81A@mail.gmail.com' \
--to=ast@plumgrid.com \
--cc=acme@infradead.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=jolsa@redhat.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masami.hiramatsu.pt@hitachi.com \
--cc=mingo@kernel.org \
--cc=namhyung@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
/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).