From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Evans Subject: Re: [PATCH v2] net: filter: BPF 'JIT' compiler for PPC64 Date: Tue, 19 Jul 2011 17:06:38 +1000 Message-ID: <4E252CFE.4070408@ozlabs.org> References: <4E23E5C3.1070209@ozlabs.org> <4E24E867.9050909@ozlabs.org> <51978BAA-10A1-483D-B551-CCC2B69C72EA@kernel.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org To: Kumar Gala Return-path: Received: from ozlabs.org ([203.10.76.45]:37925 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752294Ab1GSHGM (ORCPT ); Tue, 19 Jul 2011 03:06:12 -0400 In-Reply-To: <51978BAA-10A1-483D-B551-CCC2B69C72EA@kernel.crashing.org> Sender: netdev-owner@vger.kernel.org List-ID: On 19/07/11 16:59, Kumar Gala wrote: > > On Jul 18, 2011, at 9:13 PM, Matt Evans wrote: > >> An implementation of a code generator for BPF programs to speed up packet >> filtering on PPC64, inspired by Eric Dumazet's x86-64 version. >> >> Filter code is generated as an ABI-compliant function in module_alloc()'d mem >> with stackframe & prologue/epilogue generated if required (simple filters don't >> need anything more than an li/blr). The filter's local variables, M[], live in >> registers. Supports all BPF opcodes, although "complicated" loads from negative >> packet offsets (e.g. SKF_LL_OFF) are not yet supported. >> >> There are a couple of further optimisations left for future work; many-pass >> assembly with branch-reach reduction and a register allocator to push M[] >> variables into volatile registers would improve the code quality further. >> >> This currently supports big-endian 64-bit PowerPC only (but is fairly simple >> to port to PPC32 or LE!). >> >> Enabled in the same way as x86-64: >> >> echo 1 > /proc/sys/net/core/bpf_jit_enable >> >> Or, enabled with extra debug output: >> >> echo 2 > /proc/sys/net/core/bpf_jit_enable >> >> Signed-off-by: Matt Evans >> --- >> >> V2: Removed some cut/paste woe in setting SEEN_X even on writes. >> Merci for le review, Eric! >> >> arch/powerpc/Kconfig | 1 + >> arch/powerpc/Makefile | 3 +- >> arch/powerpc/include/asm/ppc-opcode.h | 40 ++ >> arch/powerpc/net/Makefile | 4 + >> arch/powerpc/net/bpf_jit.S | 138 +++++++ > > can we rename to bpf_jit_64.S, since this doesn't work on PPC32. > >> arch/powerpc/net/bpf_jit.h | 227 +++++++++++ >> arch/powerpc/net/bpf_jit_comp.c | 690 +++++++++++++++++++++++++++++++++ > > same here, or split between bpf_jit_comp.c (shared between ppc32 & ppc64) and > bpf_jit_comp_64.c A reasonable suggestion -- bpf_jit_64.S certainly. I think it may not be worth splitting bpf_jit_comp.c until we support both tho? (I'm thinking bpf_jit_comp_{32,64}.c would just house the stackframe generation code which is the main difference, plus compile-time switched macros for the odd LD vs LWZ.) Sorry it's not 32bit-friendly just yet (I knew you'd ask, hehe), I've postponed that for when I get a mo :-) Cheers, Matt