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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	KP Singh <kpsingh@chromium.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v5 bpf-next 2/5] bpf: Introduce sleepable BPF programs
Date: Fri, 10 Jul 2020 14:00:10 -0300
Message-ID: <20200710170010.GC7487@kernel.org> (raw)
In-Reply-To: <CAADnVQLoVfPWNBR-_56ofgaUFv8k3NT2aiGjV9jj_gOt0aoJ5g@mail.gmail.com>

Em Wed, Jul 01, 2020 at 08:21:13AM -0700, Alexei Starovoitov escreveu:
> On Wed, Jul 1, 2020 at 2:34 AM Daniel Borkmann <daniel@iogearbox.net> wrote:
> >
> > +1, I think augmenting mid-term would be the best given check_sleepable_blacklist()
> > is rather a very fragile workaround^hack and it's also a generic lsm/sec hooks issue
> 
> I tried to make that crystal clear back in march during bpf virtual conference.
> imo whitelist is just as fragile as blacklist. Underlying
> implementation can change.
> 
> > (at least for BPF_PROG_TYPE_LSM type & for the sake of documenting it for other LSMs).
> > Perhaps there are function attributes that could be used and later retrieved via BTF?
> 
> Even if we convince gcc folks to add another function attribute it
> won't appear in dwarf.

Warning, hack ahead!

Perhaps we could do that with some sort of convention, i.e. define some
type and make a function returning that type to have the desired
attribute?

I.e.

typedef __attribute__foo__int int;

__attribute__foo__int function_bla(...)
{
}

?

> So we won't be able to convert it to BTF in pahole.
> Looking at how we failed to extend address_space() attribute to
> support existing __rcu
> and __user annotations I don't have high hopes of achieving annotations
> via compiler (either gcc or clang). So plan B is to engage with sparse folks and
> make it emit BTF with __rcu, __user and other annotations.

-- 

- Arnaldo

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30  4:33 [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs Alexei Starovoitov
2020-06-30  4:33 ` [PATCH v5 bpf-next 1/5] bpf: Remove redundant synchronize_rcu Alexei Starovoitov
2020-06-30 20:55   ` Paul E. McKenney
2020-06-30  4:33 ` [PATCH v5 bpf-next 2/5] bpf: Introduce sleepable BPF programs Alexei Starovoitov
2020-06-30 22:04   ` Paul E. McKenney
2020-06-30 23:26   ` Daniel Borkmann
2020-06-30 23:41     ` Alexei Starovoitov
2020-07-01  9:15       ` KP Singh
2020-07-01  9:34         ` Daniel Borkmann
2020-07-01 15:21           ` Alexei Starovoitov
2020-07-10 17:00             ` Arnaldo Carvalho de Melo [this message]
2020-07-10 22:59               ` Alexei Starovoitov
2020-07-01  9:17       ` Daniel Borkmann
2020-07-01 15:14         ` Alexei Starovoitov
2020-07-01 19:03           ` KP Singh
2020-06-30  4:33 ` [PATCH v5 bpf-next 3/5] bpf: Add bpf_copy_from_user() helper Alexei Starovoitov
2020-06-30 11:41   ` KP Singh
2020-06-30  4:33 ` [PATCH v5 bpf-next 4/5] libbpf: support sleepable progs Alexei Starovoitov
2020-06-30  4:33 ` [PATCH v5 bpf-next 5/5] selftests/bpf: Add sleepable tests Alexei Starovoitov
2020-06-30  5:14 ` [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs Andrii Nakryiko

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