From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Murzin Subject: Re: [PATCH 1/3] net: bpf jit: ppc: optimize choose_load_func error path Date: Sun, 13 Oct 2013 16:26:09 +0200 Message-ID: <20131013142607.GB1872@hp530> References: <1381249910-17338-1-git-send-email-murzin.v@gmail.com> <52548C38.9040308@googlemail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Cc: netdev@vger.kernel.org, av1474@comtv.ru, Benjamin Herrenschmidt , Paul Mackerras , Daniel Borkmann , Matt Evans To: Jan Seiffert Return-path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:36695 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750855Ab3JMO0j (ORCPT ); Sun, 13 Oct 2013 10:26:39 -0400 Received: by mail-lb0-f174.google.com with SMTP id w6so4813099lbh.5 for ; Sun, 13 Oct 2013 07:26:37 -0700 (PDT) Content-Disposition: inline In-Reply-To: <52548C38.9040308@googlemail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Oct 09, 2013 at 12:50:32AM +0200, Jan Seiffert wrote: > Vladimir Murzin schrieb: > > Macro CHOOSE_LOAD_FUNC returns handler for "any offset" if checks for K > > were not passed. At the same time handlers for "any offset" cases make > > the same checks against r_addr at run-time, that will always lead to > > bpf_error. > > > > Hmmm, if i only would remember why i wrote it that way.... > I memory serves me right the idea was to always have a solid fall back, no > matter what, to the generic load function which works more like the load_pointer > from filter.c. > This way the COOSE-macro may could have been used at more places, but that > never played out. > > And since all i wanted was to get the negative indirect load fixed, > optimizing the constant error case was not on my plate. > That you can get your negative K filter JITed in the first place, even > if the constant error case was slower than necessary, was good enough ;) > > The ARM JIT is broken till this date... ... and s390 too. > > You can have my > I'm-OK-with-this: Jan Seiffert > > for all three patches, -ENOTIME for a full review ATM. > Thanks for feedback, Jan! > > Run-time checks are still necessary for indirect load operations, but > > error path for absolute and mesh loads are worth to optimize during bpf > > compile time. > > > > Signed-off-by: Vladimir Murzin > > > > Cc: Jan Seiffert > > Cc: Benjamin Herrenschmidt > > Cc: Paul Mackerras > > Cc: Daniel Borkmann > > Cc: Matt Evans > > > > --- > > arch/powerpc/net/bpf_jit_comp.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > > index bf56e33..754320a 100644 > > --- a/arch/powerpc/net/bpf_jit_comp.c > > +++ b/arch/powerpc/net/bpf_jit_comp.c > > @@ -132,7 +132,7 @@ static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) > > } > > > > #define CHOOSE_LOAD_FUNC(K, func) \ > > - ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) > > + ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : NULL) : func##_positive_offset) > > > > /* Assemble the body code between the prologue & epilogue. */ > > static int bpf_jit_build_body(struct sk_filter *fp, u32 *image, > > @@ -427,6 +427,11 @@ static int bpf_jit_build_body(struct sk_filter *fp, u32 *image, > > case BPF_S_LD_B_ABS: > > func = CHOOSE_LOAD_FUNC(K, sk_load_byte); > > common_load: > > + if (!func) { > > + PPC_LI(r_ret, 0); > > + PPC_JMP(exit_addr); > > + break; > > + } > > /* Load from [K]. */ > > ctx->seen |= SEEN_DATAREF; > > PPC_LI64(r_scratch1, func); > > > > > -- > An UDP packet walks into a