From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: [PATCH net-next 4/7] bpf: improve verifier liveness marks Date: Thu, 30 Nov 2017 21:31:38 -0800 Message-ID: <20171201053141.3992592-5-ast@fb.com> References: <20171201053141.3992592-1-ast@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Daniel Borkmann , John Fastabend , , To: "David S . Miller" Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:57334 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752160AbdLAFbv (ORCPT ); Fri, 1 Dec 2017 00:31:51 -0500 Received: from pps.filterd (m0001255.ppops.net [127.0.0.1]) by mx0b-00082601.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB15VnWq006049 for ; Thu, 30 Nov 2017 21:31:50 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0b-00082601.pphosted.com with ESMTP id 2ejtffs4yb-5 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Thu, 30 Nov 2017 21:31:50 -0800 In-Reply-To: <20171201053141.3992592-1-ast@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: registers with pointers filled from stack were missing live_written marks which caused liveness propagation to unnecessary mark more registers as live_read and miss state pruning opportunities later on. before after bpf_lb-DLB_L3.o 2285 2270 bpf_lb-DLB_L4.o 3723 3682 bpf_lb-DUNKNOWN.o 1110 1110 bpf_lxc-DDROP_ALL.o 27954 27876 bpf_lxc-DUNKNOWN.o 38954 38780 bpf_netdev.o 16943 16937 bpf_overlay.o 7929 7929 Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Acked-by: Daniel Borkmann --- kernel/bpf/verifier.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 14ad7c6e806a..46ff4e5b3fb7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -795,6 +795,11 @@ static int check_stack_read(struct bpf_verifier_env *env, if (value_regno >= 0) { /* restore register state from stack */ state->regs[value_regno] = state->stack[spi].spilled_ptr; + /* mark reg as written since spilled pointer state likely + * has its liveness marks cleared by is_state_visited() + * which resets stack/reg liveness for state transitions + */ + state->regs[value_regno].live |= REG_LIVE_WRITTEN; mark_stack_slot_read(state, spi); } return 0; -- 2.9.5