From: Daniel Borkmann <daniel@iogearbox•net>
To: Alexei Starovoitov <alexei.starovoitov@gmail•com>,
Jakub Kicinski <kubakici@wp•pl>
Cc: Jakub Kicinski <jakub.kicinski@netronome•com>,
netdev@vger•kernel.org, ast@kernel•org,
dinan.gunawardena@netronome•com, jiri@resnulli•us,
john.fastabend@gmail•com
Subject: Re: [RFCv2 07/16] bpf: enable non-core use of the verfier
Date: Tue, 30 Aug 2016 23:00:38 +0200 [thread overview]
Message-ID: <57C5F3F6.7040501@iogearbox.net> (raw)
In-Reply-To: <20160830204826.GA71063@ast-mbp.thefacebook.com>
On 08/30/2016 10:48 PM, Alexei Starovoitov wrote:
> On Tue, Aug 30, 2016 at 10:22:46PM +0200, Jakub Kicinski wrote:
>> On Tue, 30 Aug 2016 21:07:50 +0200, Daniel Borkmann wrote:
>>>> Having two modes seems more straight forward and I think we would only
>>>> need to pay attention in the LD_IMM64 case, I don't think I've seen
>>>> LLVM generating XORs, it's just the cBPF -> eBPF conversion.
>>>
>>> Okay, though, I think that the cBPF to eBPF migration wouldn't even
>>> pass through the bpf_parse() handling, since verifier is not aware on
>>> some of their aspects such as emitting calls directly (w/o *proto) or
>>> arg mappings. Probably make sense to reject these (bpf_prog_was_classic())
>>> if they cannot be handled anyway?
>>
>> TBH again I only use cBPF for testing. It's a convenient way of
>> generating certain instruction sequences. I can probably just drop
>> it completely but the XOR patch is just 3 lines of code so not a huge
>> cost either... I'll keep patch 6 in my tree for now.
>
> if xor matching is only need for classic, I would drop that patch
> just to avoid unnecessary state collection. The number of lines
> is not a concern, but extra state for state prunning is.
>
>> Alternatively - is there any eBPF assembler out there? Something
>> converting verifier output back into ELF would be quite cool.
>
> would certainly be nice. I don't think there is anything standalone.
> btw llvm can be made to work as assembler only, but simple flex/bison
> is probably better.
Never tried it out, but seems llvm backend doesn't have asm parser
implemented?
$ clang -target bpf -O2 -c foo.c -S -o foo.S
$ llvm-mc -arch bpf foo.S -filetype=obj -o foo.o
llvm-mc: error: this target does not support assembly parsing.
LLVM IR might work, but maybe too high level(?); alternatively, we could
make bpf_asm from tools/net/ eBPF aware for debugging purposes. If you
have a toolchain supporting libbfd et al, you could probably make use
of bpf_jit_dump() (like JITs do) and then bpf_jit_disasm tool (from
same dir as bpf_asm).
next prev parent reply other threads:[~2016-08-30 21:00 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-26 18:05 [RFCv2 00/16] BPF hardware offload (cls_bpf for now) Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 01/16] add basic register-field manipulation macros Jakub Kicinski
2016-08-29 14:34 ` Daniel Borkmann
2016-08-29 15:07 ` Jakub Kicinski
2016-08-29 15:40 ` Daniel Borkmann
2016-08-26 18:06 ` [RFCv2 02/16] net: cls_bpf: add hardware offload Jakub Kicinski
2016-08-29 14:51 ` Daniel Borkmann
2016-08-26 18:06 ` [RFCv2 03/16] net: cls_bpf: limit hardware offload by software-only flag Jakub Kicinski
2016-08-29 15:06 ` Daniel Borkmann
2016-08-29 15:15 ` Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 04/16] net: cls_bpf: add support for marking filters as hardware-only Jakub Kicinski
2016-08-29 15:28 ` Daniel Borkmann
2016-08-26 18:06 ` [RFCv2 05/16] bpf: recognize 64bit immediate loads as consts Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 06/16] bpf: verifier: recognize rN ^ rN as load of 0 Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 07/16] bpf: enable non-core use of the verfier Jakub Kicinski
2016-08-26 23:29 ` Alexei Starovoitov
2016-08-27 11:40 ` Jakub Kicinski
2016-08-27 17:32 ` Alexei Starovoitov
2016-08-29 20:13 ` Daniel Borkmann
2016-08-29 20:17 ` Daniel Borkmann
2016-08-30 10:48 ` Jakub Kicinski
2016-08-30 19:07 ` Daniel Borkmann
2016-08-30 20:22 ` Jakub Kicinski
2016-08-30 20:48 ` Alexei Starovoitov
2016-08-30 21:00 ` Daniel Borkmann [this message]
2016-08-31 1:18 ` Alexei Starovoitov
2016-08-26 18:06 ` [RFCv2 08/16] bpf: export bpf_prog_clone functions Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 09/16] nfp: add BPF to NFP code translator Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 10/16] nfp: bpf: add hardware bpf offload Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 11/16] net: cls_bpf: allow offloaded filters to update stats Jakub Kicinski
2016-08-29 20:43 ` Daniel Borkmann
2016-08-26 18:06 ` [RFCv2 12/16] net: bpf: " Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 13/16] nfp: bpf: add packet marking support Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 14/16] net: act_mirred: allow statistic updates from offloaded actions Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 15/16] nfp: bpf: add support for legacy redirect action Jakub Kicinski
2016-08-26 18:06 ` [RFCv2 16/16] nfp: bpf: add offload of TC direct action mode Jakub Kicinski
2016-08-29 21:09 ` Daniel Borkmann
2016-08-30 10:52 ` Jakub Kicinski
2016-08-30 20:02 ` Daniel Borkmann
2016-08-30 20:50 ` Jakub Kicinski
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