From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kumar Gala Subject: Re: [PATCH v2] net: filter: BPF 'JIT' compiler for PPC64 Date: Tue, 19 Jul 2011 02:17:31 -0500 Message-ID: References: <4E23E5C3.1070209@ozlabs.org> <4E24E867.9050909@ozlabs.org> <51978BAA-10A1-483D-B551-CCC2B69C72EA@kernel.crashing.org> <4E252CFE.4070408@ozlabs.org> Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org To: Matt Evans Return-path: Received: from gate.crashing.org ([63.228.1.57]:55584 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752174Ab1GSHRl convert rfc822-to-8bit (ORCPT ); Tue, 19 Jul 2011 03:17:41 -0400 In-Reply-To: <4E252CFE.4070408@ozlabs.org> Sender: netdev-owner@vger.kernel.org List-ID: On Jul 19, 2011, at 2:06 AM, Matt Evans wrote: > 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.) If its most 64-bit specific than just go with bpf_jit_comp_64.c for now. We can refactor later. > > Sorry it's not 32bit-friendly just yet (I knew you'd ask, hehe), I've postponed > that for when I get a mo :-) :)