From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x233.google.com (mail-wm0-x233.google.com [IPv6:2a00:1450:400c:c09::233]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id C6D0A3CB35 for ; Wed, 22 Aug 2018 05:37:15 -0400 (EDT) Received: by mail-wm0-x233.google.com with SMTP id i134-v6so11582333wmf.0 for ; Wed, 22 Aug 2018 02:37:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=heistp.net; s=google; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=zutwD/qnNKAZXGb6N9BTS4LNw/3LGSkcCSdza9/s2qs=; b=CqA3g9fWOysFHMtk/frBfLtR52aFCpy09ZlUULJspDmp/rAyP8V6LAdVUSyNJmQkzw HXLOGfrRvB2dDsD8JI595dZcUiW4AS00NPWzWqYDOk25u/XImZGRvwWZ/iTvR6HtKOwR DnONOPA77OCMqHCDZP8vPGNWTLsPzGVjydEGNrYnHLe4qEaAxSAj7YsHUzhStTm/u1DY NsGsn6qsYPsfwIntPvDBgaIaCUoW9/44BwTd84PeeQgXmWnJ56TKijHN65alssvMYp5K LaSm+f3WLUfRjNIFImW4pwHj8k3/XH8PoJO48lluQdfZWw7mjAZCbGf8FlDKfNt+/QQC WDSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=zutwD/qnNKAZXGb6N9BTS4LNw/3LGSkcCSdza9/s2qs=; b=i6I11VA/K9QUej6lfJgVlJ6/7WZNovImcf2BJuaqV/m78Z+FDoATx7jqlCPSwNHl9V 8xLbeD7W2ntfI3Kpz5CHHOVGH8a6GJWje6uh1k1s/ePnjhKft9j5Iq+y7CZjfn1yuxJi tnYMYchQRgv5Qng8Uh6mU8Jpo+OPBV2PN48vtRD7ZydOp60m9VRF9BDiT0EPoclYptke rtWi9gK5jssA3sahpU/M3l2mWUsGNniYGEmlQMylETn2SqnkMwYO/hFYwBfBbKklmuoM bewoM7J1ontEpbmcuOFACGxmvrfNLPl1qOqlGQDn5kPN1sLb1fGdGXKK+zNzgpesbl2W iGUQ== X-Gm-Message-State: APzg51Cau/LytvGg+5SrWYYKZlNtz9nBEo8gG0XpVc2yONUEwPW4Fn89 V5oQc15uovYK1AlRpsZtGjR9Fg== X-Google-Smtp-Source: ANB0VdZmvEiogSMTTvSRuxMrvZ1qGZKcZq3KfdwuxVowvcK3NlaqnixXF1kVT3LmKLpIvVIKnxKP6Q== X-Received: by 2002:a1c:7915:: with SMTP id l21-v6mr1844737wme.136.1534930634973; Wed, 22 Aug 2018 02:37:14 -0700 (PDT) Received: from tron.lt2.drhleny.cz ([185.15.109.151]) by smtp.gmail.com with ESMTPSA id w10-v6sm829024wrp.31.2018.08.22.02.37.14 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Aug 2018 02:37:14 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Pete Heist In-Reply-To: <871saqah2m.fsf@toke.dk> Date: Wed, 22 Aug 2018 11:37:13 +0200 Cc: Dave Taht , Cake List Content-Transfer-Encoding: quoted-printable Message-Id: References: <20180816164423.14368-1-peterpenkov96@gmail.com> <20180816164423.14368-3-peterpenkov96@gmail.com> <5E9B5665-E115-4B8B-959A-0A4A4220046A@heistp.net> <871saqah2m.fsf@toke.dk> To: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Cake] [bpf-next RFC 2/3] flow_dissector: implements eBPF parser X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Aug 2018 09:37:16 -0000 > On Aug 22, 2018, at 11:25 AM, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >=20 > Pete Heist writes: >=20 >> The eBPF verifier seems fragile to me, where I=E2=80=99d be moving = lines of >> code around and getting different error messages in an alien tongue. >=20 > Well, it operates on the byte code and errs on the side of safety. = I.e., > if it can't prove your program is safe it is going to reject it. Which > can be less than helpful. Yes, understood. I just found it sensitive to the place where variables = are initialized, for example, even when the code looked equivalent. = I=E2=80=99ll present a concrete example to them when I see it again. > There's a mode where it can dump its state including the byte code it = is > operating at, which can be helpful in figuring out why you get an = error. > But it has a way to go yet compared with regular compiler error > messages... :) Yes, as examples: "R2 type=3Dinv expected=3Dfp=E2=80=9D (which I think = means that a value should was expected to be on the stack but was not) = or "math between pkt pointer and 4294901760 is not allowed=E2=80=9D, = might not suggest what one needs to do, although there are hints = available if one searches=E2=80=A6 :)