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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>,
	bpf <bpf@vger.kernel.org>, Luka Perkov <luka.perkov@sartura.hr>,
	David Marcinkovic <david.marcinkovic@sartura.hr>
Subject: Re: Running JITed and interpreted programs simultaneously
Date: Mon, 19 Oct 2020 15:02:16 -0700	[thread overview]
Message-ID: <CAADnVQLLQnyiwnw8jPxgJtb59t78wz8X6JQZhTxUe0gw+yRz7w@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzatiTgwSqyP8tJRM32YWyHe1QSDEQWKezWTHE9ocLcgjQ@mail.gmail.com>

On Mon, Oct 19, 2020 at 11:26 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> That wasn't happening last time people reported this on ARM32.
> BPF_XADD was causing load failure, no fail back to interpreter mode.
>
> >
> > Wrt force-interpret vs force-jit BPF_PROG_LOAD flag, I'm more concerned that this
> > decision will then be pushed to the user who should not have to care about these
> > internals. And how would generic loaders try to react if force-jit fails? They would
> > then fallback to force-interpret same way as kernel does?
>
> The way I imagined this was if the user wants to force the mode and
> the kernel doesn't support it (or the program can't be loaded in that
> mode), then it's a fail-stop, no fall back. And it's strictly an
> opt-in flag, if nothing is specified then it's current behavior with
> fallback (which apparently doesn't always work).

That doesn't sound right.
Fallback to interpreter should always work unless features like
trampoline are used.
But that's not the case for arm32. Missing xadd support shouldn't cause
load failure.

  reply	other threads:[~2020-10-19 22:02 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09 18:40 Running JITed and interpreted programs simultaneously Juraj Vijtiuk
2020-10-13 22:05 ` Andrii Nakryiko
2020-10-19 10:20   ` Juraj Vijtiuk
2020-10-19 12:58     ` Daniel Borkmann
2020-10-19 18:26       ` Andrii Nakryiko
2020-10-19 22:02         ` Alexei Starovoitov [this message]
2020-10-20 20:56           ` Juraj Vijtiuk

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