From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [PATCHv4 net-next 07/15] bpf: recognize 64bit immediate loads as consts Date: Thu, 15 Sep 2016 13:12:15 -0700 Message-ID: <20160915201214.GC74433@ast-mbp.thefacebook.com> References: <1473966755-30106-1-git-send-email-jakub.kicinski@netronome.com> <1473966755-30106-8-git-send-email-jakub.kicinski@netronome.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, jiri@resnulli.us, john.fastabend@gmail.com, kubakici@wp.pl To: Jakub Kicinski Return-path: Received: from mail-pa0-f67.google.com ([209.85.220.67]:34456 "EHLO mail-pa0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752280AbcIOUMU (ORCPT ); Thu, 15 Sep 2016 16:12:20 -0400 Received: by mail-pa0-f67.google.com with SMTP id vz6so2524080pab.1 for ; Thu, 15 Sep 2016 13:12:20 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1473966755-30106-8-git-send-email-jakub.kicinski@netronome.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Sep 15, 2016 at 08:12:27PM +0100, Jakub Kicinski wrote: > When running as parser interpret BPF_LD | BPF_IMM | BPF_DW > instructions as loading CONST_IMM with the value stored > in imm. The verifier will continue not recognizing those > due to concerns about search space/program complexity > increase. > > Signed-off-by: Jakub Kicinski > --- > v3: > - limit to parsers. > --- > kernel/bpf/verifier.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index d93e78331b90..f5bed7cce08d 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -1766,9 +1766,19 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) > if (err) > return err; > > - if (insn->src_reg == 0) > - /* generic move 64-bit immediate into a register */ > + if (insn->src_reg == 0) { > + /* generic move 64-bit immediate into a register, > + * only analyzer needs to collect the ld_imm value. > + */ > + u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; > + > + if (!env->analyzer_ops) > + return 0; the check makes sense. thanks. Acked-by: Alexei Starovoitov