From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67595C43381 for ; Wed, 27 Mar 2019 16:35:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29CB72082F for ; Wed, 27 Mar 2019 16:35:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="trkOAUSy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727389AbfC0QfJ (ORCPT ); Wed, 27 Mar 2019 12:35:09 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:40940 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727087AbfC0QfJ (ORCPT ); Wed, 27 Mar 2019 12:35:09 -0400 Received: by mail-pg1-f196.google.com with SMTP id u9so10179423pgo.7; Wed, 27 Mar 2019 09:35:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=6jHg8Zc9oA4ImwCHws9l8N+YT23p/v70upnm1qqJ9CU=; b=trkOAUSyC+3FY7qv/McUf9TTA52IKfrx19qG7eS/0JK5c9aAYCyFOMzyWiVD1WyY6B ODCw13tzoJYBvdjypezfC5KMKGY2/euZIRaOP7oqD47Jq9XfoHfKnza+4GmVeLdIecrL bn9xaZ/JdzQXiFL/c2piLVJr14tHqnleO37iPcm+N9wYBxPOBKfkDe493ogRc5IL1Yra u0P8thB41tFddb7BcsAwnYxnb+kV4hiXM7zaXxjNNp01nt99RRQ67rROr8a5+6uKPpsg pvjj6kGdm7tnbVVACuSZUFYVtMyCH6yqsaahy8BSZYROOVD9rhabfao0LNlJvuZGzLSc 9gRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=6jHg8Zc9oA4ImwCHws9l8N+YT23p/v70upnm1qqJ9CU=; b=jY/r409PJ5I/yZshOBuNw9WgbFqLRXP/f+V6BTIjShnPAHgk1oo+mDcqnTKID+ADjE DOXhn+JaU6gyXSg5XuT6QX8uiN607w04TkfUnUrLWNcLSto0KLrY8tK50m24XIj00pA6 q9MGE09uITDkQINT0o+IkzfEKAd2aB1UT5kgpxMFc6dIg8btQp4c3oHdd90eU7oG2l1k +0s+xzg9II5XWkk+/Jc9x8y5ZKlRUeqWUBcIc67FpiIizmRx8EF5j5Gnw5THsiQc4mLK J61ymCtrQGz3xMgG3LwIDEpmyBHchwh/rm6mTBqQ8aKCsNEm0auADY8LTsaojlaVWBhk HIzg== X-Gm-Message-State: APjAAAUeyrvMg8T7R1KMMQNYacnjuSJ/Udq7FDQT0Sn4qwbMrRRPlYUg f/6izCfNcg64FYVbtxzSr7A= X-Google-Smtp-Source: APXvYqxTlvv6+ODCXbAbE5wLsRciGlD3AtaqPj3K2ebhOFT+w5LaVJM0rRJ0RYa4cv+PaZV0AsaxoQ== X-Received: by 2002:aa7:8443:: with SMTP id r3mr35765040pfn.143.1553704508364; Wed, 27 Mar 2019 09:35:08 -0700 (PDT) Received: from ast-mbp ([2620:10d:c090:180::ca40]) by smtp.gmail.com with ESMTPSA id l187sm27298136pgl.75.2019.03.27.09.35.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Mar 2019 09:35:07 -0700 (PDT) Date: Wed, 27 Mar 2019 09:35:05 -0700 From: Alexei Starovoitov To: Jiong Wang Cc: daniel@iogearbox.net, bpf@vger.kernel.org, netdev@vger.kernel.org, oss-drivers@netronome.com Subject: Re: [PATCH/RFC bpf-next 02/16] bpf: refactor propagate_live implementation Message-ID: <20190327163504.7ueecpetrwohkbmd@ast-mbp> References: <1553623539-15474-1-git-send-email-jiong.wang@netronome.com> <1553623539-15474-3-git-send-email-jiong.wang@netronome.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1553623539-15474-3-git-send-email-jiong.wang@netronome.com> User-Agent: NeoMutt/20180223 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Mar 26, 2019 at 06:05:25PM +0000, Jiong Wang wrote: > Some code inside current implementation of "propagate_liveness" is a little > bit verbose. > > This patch refactor them so the code looks more simple and more clear. > > The redundant usage of "vparent->frame[vstate->curframe]" is removed as we > are here. It is safe to do this because "state_equal" has guaranteed that > vstate->curframe must be equal with vparent->curframe. > > Signed-off-by: Jiong Wang > --- > kernel/bpf/verifier.c | 44 ++++++++++++++++++++++++++++++-------------- > 1 file changed, 30 insertions(+), 14 deletions(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 6cc8c38..245bb3c 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -6050,6 +6050,22 @@ static bool states_equal(struct bpf_verifier_env *env, > return true; > } > > +static int propagate_liveness_reg(struct bpf_verifier_env *env, > + struct bpf_reg_state *reg, > + struct bpf_reg_state *parent_reg, u8 flag) > +{ > + int err; > + > + if (parent_reg->live & flag || !(reg->live & flag)) > + return 0; > + > + err = mark_reg_read(env, reg, parent_reg); > + if (err) > + return err; > + > + return 1; > +} what is the difference between 1 and 0 ? it doesn't seem to be used. > + > /* A write screens off any subsequent reads; but write marks come from the > * straight-line code between a state and its parent. When we arrive at an > * equivalent state (jump target or such) we didn't arrive by the straight-line > @@ -6061,8 +6077,9 @@ static int propagate_liveness(struct bpf_verifier_env *env, > const struct bpf_verifier_state *vstate, > struct bpf_verifier_state *vparent) > { > - int i, frame, err = 0; > + struct bpf_reg_state *regs, *parent_regs; > struct bpf_func_state *state, *parent; > + int i, frame, err = 0; > > if (vparent->curframe != vstate->curframe) { > WARN(1, "propagate_live: parent frame %d current frame %d\n", > @@ -6071,16 +6088,13 @@ static int propagate_liveness(struct bpf_verifier_env *env, > } > /* Propagate read liveness of registers... */ > BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); > + parent_regs = vparent->frame[vparent->curframe]->regs; > + regs = vstate->frame[vstate->curframe]->regs; may be do: frame = vstate->curframe; if (vparent->curframe != frame) { WARN... parent_regs = vparent->frame[frame]->regs; regs = vstate->frame[frame]->regs; ? > /* We don't need to worry about FP liveness because it's read-only */ > for (i = 0; i < BPF_REG_FP; i++) { > - if (vparent->frame[vparent->curframe]->regs[i].live & REG_LIVE_READ) > - continue; > - if (vstate->frame[vstate->curframe]->regs[i].live & REG_LIVE_READ) { > - err = mark_reg_read(env, &vstate->frame[vstate->curframe]->regs[i], > - &vparent->frame[vstate->curframe]->regs[i]); > - if (err) > - return err; > - } > + err = propagate_liveness_reg(env, ®s[i], &parent_regs[i]); > + if (err < 0) > + return err; > } > > /* ... and stack slots */ > @@ -6089,11 +6103,13 @@ static int propagate_liveness(struct bpf_verifier_env *env, > parent = vparent->frame[frame]; > for (i = 0; i < state->allocated_stack / BPF_REG_SIZE && > i < parent->allocated_stack / BPF_REG_SIZE; i++) { > - if (parent->stack[i].spilled_ptr.live & REG_LIVE_READ) > - continue; > - if (state->stack[i].spilled_ptr.live & REG_LIVE_READ) > - mark_reg_read(env, &state->stack[i].spilled_ptr, > - &parent->stack[i].spilled_ptr); > + struct bpf_reg_state *parent_reg, *reg; > + > + parent_reg = &parent->stack[i].spilled_ptr; > + reg = &state->stack[i].spilled_ptr; > + err = propagate_liveness_reg(env, reg, parent_reg); > + if (err < 0) > + return err; > } > } > return err; > -- > 2.7.4 >