From: Hagen Paul Pfeifer <hagen@jauu.net>
To: Daniel Borkmann <dborkman@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>,
"David S. Miller" <davem@davemloft.net>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Tom Zanussi <tom.zanussi@linux.intel.com>,
Jovi Zhangwei <jovi.zhangwei@gmail.com>,
Eric Dumazet <edumazet@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Pekka Enberg <penberg@iki.fi>,
Arjan van de Ven <arjan@infradead.org>,
Christoph Hellwig <hch@infradead.org>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
Jesse Gross <jesse@nicira.com>
Subject: Re: [PATCH v3 net-next 1/1] bpf32->bpf64 mapper and bpf64 interpreter
Date: Mon, 3 Mar 2014 11:05:01 +0100 [thread overview]
Message-ID: <20140303100501.GB1108@localhost.localdomain> (raw)
In-Reply-To: <53112A08.5080309@redhat.com>
* Daniel Borkmann | 2014-03-01 01:30:00 [+0100]:
>>>as in 'struct bpf_insn' the immediate value is 32 bit, so for 64 bit
>>>comparisons, you'd still need to load to immediate values, right?
>>
>>there is no insn that use 64-bit immediate, since 64-bit immediates
>>are extremely rare. grep x86-64 asm code for movabsq will return very few.
>>llvm or gcc can easily construct any constant by combination of mov,
>>shifts and ors.
>>bpf64 comparisons are all 64-bit right now. So far I didn't see a need to do
>>32-bit comparison, since old bpf is all unsigned, mapping 32->64 of
>>Jxx is painless.
>
>Hm, fair enough, I was just thinking for comparisons of IPv6 addresses
>when we do socket filtering. On the other hand, old and new insns are
>both 64 bit wide and can be used though the same api then.
What about the long term idea to support JITed nftables? A 128 bit immediate
is required - maybe the biggest requirement for nftable support.
Hagen
next prev parent reply other threads:[~2014-03-03 10:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-27 2:38 [PATCH v3 net-next 0/1] bpf32->bpf64 mapper and bpf64 interpreter Alexei Starovoitov
2014-02-27 2:38 ` [PATCH v3 net-next 1/1] " Alexei Starovoitov
2014-02-28 12:45 ` Daniel Borkmann
2014-02-28 20:53 ` Alexei Starovoitov
2014-03-01 0:10 ` Alexei Starovoitov
2014-03-01 0:30 ` Daniel Borkmann
2014-03-03 10:05 ` Hagen Paul Pfeifer [this message]
2014-03-03 23:04 ` Alexei Starovoitov
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