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From: Thomas Gleixner <tglx@linutronix.de>
To: Kees Cook <keescook@chromium.org>
Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	David Miller <davem@davemloft.net>,
	bpf@vger.kernel.org, netdev@vger.kernel.org,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Sebastian Sewior <bigeasy@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Clark Williams <williams@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Ingo Molnar <mingo@kernel.org>, Will Drewry <wad@chromium.org>,
	Andy Lutomirski <luto@kernel.org>
Subject: Re: [RFC patch 09/19] bpf: Use BPF_PROG_RUN_PIN_ON_CPU() at simple call sites.
Date: Fri, 21 Feb 2020 15:00:54 +0100
Message-ID: <87lfownip5.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <202002201616.21FA55E@keescook>

Kees Cook <keescook@chromium.org> writes:
> On Wed, Feb 19, 2020 at 10:00:56AM +0100, Thomas Gleixner wrote:
>> Vinicius Costa Gomes <vinicius.gomes@intel.com> writes:
>> > More a question really, isn't the behavior changing here? i.e. shouldn't
>> > migrate_disable()/migrate_enable() be moved to outside the loop? Or is
>> > running seccomp filters on different cpus not a problem?
>> 
>> In my understanding this is a list of filters and they are independent
>> of each other.
>> 
>> Kees, Will. Andy?
>
> They're technically independent, but they are related to each
> other. (i.e. order matters, process hierarchy matters, etc). There's no
> reason I can see that we can't switch CPUs between running them, though.
> (AIUI, nothing here would suddenly make these run in parallel, right?)

Of course not. If we'd run the same thread on multiple CPUs in parallel
the ordering of your BPF programs would be the least of your worries.

> As long as "current" is still "current", and they run in the same order,
> we'll get the same final result as far as seccomp is concerned.

Right.

Thanks,

        tglx

  reply index

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-14 13:39 [RFC patch 00/19] bpf: Make BPF and PREEMPT_RT co-exist Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 01/19] sched: Provide migrate_disable/enable() inlines Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 02/19] sched: Provide cant_migrate() Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 03/19] bpf: Update locking comment in hashtab code Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 04/19] bpf/tracing: Remove redundant preempt_disable() in __bpf_trace_run() Thomas Gleixner
2020-02-19 16:54   ` Steven Rostedt
2020-02-19 17:26     ` Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 05/19] perf/bpf: Remove preempt disable around BPF invocation Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 06/19] bpf: Dont iterate over possible CPUs with interrupts disabled Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 07/19] bpf: Provide BPF_PROG_RUN_PIN_ON_CPU() macro Thomas Gleixner
2020-02-14 18:50   ` Mathieu Desnoyers
2020-02-14 19:36     ` Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 08/19] bpf: Replace cant_sleep() with cant_migrate() Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 09/19] bpf: Use BPF_PROG_RUN_PIN_ON_CPU() at simple call sites Thomas Gleixner
2020-02-19  1:39   ` Vinicius Costa Gomes
2020-02-19  9:00     ` Thomas Gleixner
2020-02-19 16:38       ` Alexei Starovoitov
2020-02-21  0:20       ` Kees Cook
2020-02-21 14:00         ` Thomas Gleixner [this message]
2020-02-21 14:05           ` Peter Zijlstra
2020-02-21 22:15           ` Kees Cook
2020-02-14 13:39 ` [RFC patch 10/19] trace/bpf: Use migrate disable in trace_call_bpf() Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 11/19] bpf/tests: Use migrate disable instead of preempt disable Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 12/19] bpf: Use migrate_disable/enabe() in trampoline code Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 13/19] bpf: Use migrate_disable/enable in array macros and cgroup/lirc code Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 14/19] bpf: Use migrate_disable() in hashtab code Thomas Gleixner
2020-02-14 19:11   ` Mathieu Desnoyers
2020-02-14 19:56     ` Thomas Gleixner
2020-02-18 23:36       ` Alexei Starovoitov
2020-02-19  0:49         ` Thomas Gleixner
2020-02-19  1:23           ` Alexei Starovoitov
2020-02-19 15:17         ` Mathieu Desnoyers
2020-02-20  4:19           ` Alexei Starovoitov
2020-02-14 13:39 ` [RFC patch 15/19] bpf: Use migrate_disable() in sys_bpf() Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 16/19] bpf: Factor out hashtab bucket lock operations Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 17/19] bpf: Prepare hashtab locking for PREEMPT_RT Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 18/19] bpf, lpm: Make locking RT friendly Thomas Gleixner
2020-02-14 13:39 ` [RFC patch 19/19] bpf/stackmap: Dont trylock mmap_sem with PREEMPT_RT and interrupts disabled Thomas Gleixner
2020-02-14 17:53 ` [RFC patch 00/19] bpf: Make BPF and PREEMPT_RT co-exist David Miller
2020-02-14 18:36   ` Thomas Gleixner
2020-02-17 12:59     ` [PATCH] bpf: Enforce map preallocation for all instrumentation programs Thomas Gleixner
2020-02-15 20:09 ` [RFC patch 00/19] bpf: Make BPF and PREEMPT_RT co-exist Jakub Kicinski

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