From: Mark Rutland <mark.rutland@arm.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Florent Revest <revest@chromium.org>, bpf <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
KP Singh <kpsingh@kernel.org>,
Brendan Jackman <jackmanb@google.com>,
markowsky@google.com, Steven Rostedt <rostedt@goodmis.org>,
Xu Kuohai <xukuohai@huawei.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 0/1] BPF tracing for arm64 using fprobe
Date: Fri, 18 Nov 2022 16:26:34 +0000 [thread overview]
Message-ID: <Y3eyOpVg1dgP1Gjv@FVFF77S0Q05N.cambridge.arm.com> (raw)
In-Reply-To: <CAADnVQJgWb36eLEPqcChiVTUikSMU5UNAdo30fD7H8xFiE2E1w@mail.gmail.com>
Hi Alexei,
On Thu, Nov 17, 2022 at 08:50:12AM -0800, Alexei Starovoitov wrote:
> There might not be a task available where bpf trampoline is running.
I'm not sure what you mean by "there might not be a task available"; do you
mean that there might not be space in the per-task shadow stack, or that the
BPF program can be invoked inan IRQ context?
> rcu protection might not be there either.
We've spent a lot of time reworking entry/idle sequences with noinstr, so any
time BPF can be invoked, we should have a regular kernel environment available,
with RCU watching (but not necessarily in an RCU read-side critical section).
If BPF is being invoked without RCU watching, that is a bug that needs to be
fixed.
Do you have a specific example in mind?
Thanks,
Mark.
next prev parent reply other threads:[~2022-11-18 16:26 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 22:06 Florent Revest
2022-11-08 22:06 ` [RFC 1/1] bpf: Invoke tracing progs using fprobe on archs without direct call Florent Revest
2022-11-17 2:41 ` [RFC 0/1] BPF tracing for arm64 using fprobe Alexei Starovoitov
2022-11-17 13:33 ` Masami Hiramatsu
2022-11-17 16:50 ` Alexei Starovoitov
2022-11-18 16:26 ` Mark Rutland [this message]
2022-11-17 17:16 ` Steven Rostedt
2022-11-17 21:55 ` Chris Mason
2022-11-17 22:40 ` Steven Rostedt
2022-11-18 16:34 ` Mark Rutland
2022-11-18 16:45 ` Steven Rostedt
2022-11-18 17:44 ` Chris Mason
2022-11-18 18:06 ` Steven Rostedt
2022-11-18 18:52 ` Chris Mason
2022-11-21 13:47 ` KP Singh
2022-11-21 14:16 ` Peter Zijlstra
2022-11-21 14:23 ` KP Singh
2022-11-21 15:15 ` Steven Rostedt
2022-11-21 15:29 ` KP Singh
2022-11-21 15:39 ` Steven Rostedt
2022-11-21 16:16 ` Jiri Kosina
2022-11-21 15:40 ` Alexei Starovoitov
2022-11-21 15:45 ` Steven Rostedt
2022-11-21 15:55 ` Borislav Petkov
2022-11-21 10:09 ` Peter Zijlstra
2022-11-21 14:40 ` Masami Hiramatsu
2022-11-18 16:18 ` Mark Rutland
2022-11-17 13:16 ` Masami Hiramatsu
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